Funnily enough, though, it's not the 'big stuff' that really makes GTA IV so special (though it certainly helps). Instead it's the little things that bring Liberty City to life in a way no previous game world has been brought to life before.

A great example of what I'm babbling on about occurs pretty much as soon as you've booted the game up. Following a wonderfully cinematic opening credits sequence, you end up at your cousin's flat and have the option to watch TV. Settle down to do just that, and you can end up sitting there for the best part of an hour - repeat, an hour - watching two channels of 'TV' shows originally written and animated just for this game.

As if this wasn't jaw-dropping enough in its bravado and the way it helps create the impression that you're leading a second life in GTAIV rather than just playing a game, every minute of the TV footage is brilliant; hilarious, irreverent and adult parodies of TV's worst types of show. Honestly, there's more wit and entertainment in these completely throwaway TV shows than most games can fit into their entire length.

In fact, one of the TV shows, a piss-take of Cribs, even provided me with the perfect ambition to carry with me as I played through the game: to get rich enough to own a dragon that shits pizza. Booyah.

Of course, putting this TV and its programmes in the very first location you enter in the game is a very clever move. For it immediately opens your eyes to the level of loving detail Rockstar has put into Liberty City, and thus encourages you to just 'hang out' for ages enjoying other areas of the game too - almost always with wonderfully rewarding results.

Want to just go to a bar and shoot some pool or play darts? You can. Want to go to a strip club and just sit there watching for ages? Or order a private dance? No problem. Want to go to an internet café and surf the web (bringing up hilarious and extensive parodies of typical website crap), send emails or join online dating agencies? Easy. Want to get pissed and try and stagger home? Fill your boots. Want to just ride around in the sunshine taking in the sights from an open top car with a favourite tune banging out of the radio? Then do it. And so I could go on. And on. And on.

Even more remarkable is the amount of effort that's gone into making these mere pastimes feel real. The amount of dialogue between yourself and the characters you hang out with is staggering, for instance - and brilliantly scripted and acted from start to finish. Then there's the way that if you go to a show, you actually get to watch not one but two different acts performing.

And these are just a paltry few examples of the sort of rich, 'life-tapestry' bits and bobs found tucked away in every corner of Liberty City, included for you to check out not because they're critical to finishing the game, but just because you might want to check them out.

In other words, Rockstar has succeeded - possibly for the first time in a sandbox title - in making simply living your character's life feel more like the object of the game than getting a few missions done.

Even finishing the game doesn't feel like any sort of conscious aim/motivation; it's just something that you might end up doing at some point simply as a natural part of the amount of time you've spent living your alternative Liberty City life. Especially as the pace of character progression and the game's difficulty curve are so subtle and immaculately judged during the game's missions that you're hardly ever jarred out of the game's narrative world.

So much for the game's 'big idea'; its life-sapping and really pretty revolutionary balance of 'big and small' in recreating a city. Getting into the more specific stuff - shooting, driving, generally running about - Grand Theft Auto IV both pleases and occasionally irritates.

Pleasing is how much slicker and more manageable nearly every aspect of the gameplay feels versus the previous GTA game, San Andreas.

For starters, the way a cellphone is used to provide all the information you need to know and select various in-game options works sublimely well, providing a brilliant alternative to entering distracting menus outside of the game environment like you have to with most games.

Also improved is the game's driving engine, which feels much more realistic with its handling, and more adaptive to the incredible variety of vehicles at your disposal. Drive a performance sports car, and you feel like you're driving a performance sports car. Drive a trash truck, and you feel like you're driving a trash truck. Even crashes look and feel more in tune with the kind of vehicle you're driving than they used to.

Fisticuffs has been much improved from GTAs of the past, too. Now you've got far more fighting options available to you, making a good scrap actually feel like there's some skill involved, rather than a mere button-mashing exercise.

Running is also better, as you can now sprint for much greater distances than before with carefully timed pumps of the A button.

Even better, you can now 'Freerun' over rooftops. Admittedly the need to check that some of the leaps you're about to make aren't going to cause you to fall too far limits the Freerunning possibilities a little. But it's certainly possible to put some truly exhilarating sequences together.

Last but not least, the game's shooting sections are easily the best yet on a GTA game thanks to the addition of a more sophisticated targeting system and, best of all, the facility to take cover behind scenery, and shoot 'blind' from there without having to risk getting a cap in your ass.

The bad news is that while every aspect of all the multiple gameplay types GTA crams in has been beefed up, learning all the new controls for each section so that they become second nature will prove a really lengthy undertaking. During which time you'll doubtless die many times as a result of forgetting which button to press at a critical moment.

What's more, none of the game types - including the pool, darts and especially bowling minigames - feels completely perfect or entirely intuitive in their control, even now after I've been playing the game for tens of hours. For instance, if I had a dollar for every time I'd fannied around for an eternity at the bottom of a ladder trying to get Nico to just go up the bloody thing, I'd easily have earned my '$500,000' Xbox 360 achievement by now. And I've had some pretty nasty experiences getting stuck on 'cover' scenery, too.

There are other real aggravations about the game, too - particularly elements of the multiplayer experience (see our Online Elements section) and the occasional moment where Rockstar actually takes the generally brilliant 'realism' approach a touch too far.

The police, in particular, are just too overbearing. There's nothing more annoying than getting right near the end of a long, hard mission and accidentally clipping a police car as you round a corner, resulting in a sometimes lengthy chase across Liberty City and even, potentially, you getting arrested so that you have to start the mission all over again.

Even worse - and this really winds me up - if you get arrested you lose all of your weapons. This isn't such a big deal later in the game when you've got plenty of cash behind you to buy new weapons with, but early on replacing your shooters is so annoyingly expensive that you're more likely to just shut the console down and start again from the save game you had before the last mission started. Even if that means spending ages running around eating hot dogs to regain health and buying up more ammo before you dare actually restart the mission properly.

I guess one final accusation you could level at GTA IV's gameplay is that it can be rather repetitive. Most missions are pretty much wash and repeats of 'Drive here, shoot somebody, drive there, ring a contact, job done'. What's more, there's precious little in the game's disappointingly staid Xbox Achievements list that might have tempted you to try and play things out in any really different ways.

However, my experience is that things only start to feel repetitive if you decide to just put your head down and 'grind' through the missions. Do as Rockstar wants you to and enjoy plenty of downtime between the main story missions, and the game hardly ever feels repetitive at all.

After loving Crackdown so much last year, with its crazy stunts and building-high jumps, I'd honestly had my doubts that I could ever really enjoy another GTA game again. But GTA IV puts me straight in no uncertain terms, proving that if you can cram a sandbox game environment full of enough character, detail and things to do, the fact that your character can only jump a couple of feet off the floor doesn't mean jack.

But with every minute I've spent in Liberty City - and there have been a lot! - the game's graphics have just grown and grown on me.

The single most important thing to realise about them is that they're stylised to create ambience and atmosphere. As a result, instead of the rather clinical look of Saint's Row or even, to a lesser extent, the latest Burnout's Paradise City, you get a city that feels completely alive, with different 'vibes' as you drive from area to area.

What's more, unlike the 'identikit' feel to the streets of many sandbox cities, here every single yard of every single street looks completely unique. Even the random citizens wandering Liberty City's streets look different enough to fool you into thinking they’re all individuals, thanks to the large amount of character models the game uses - and that's something not even that big graphics show off known as Assassin's Creed can claim.

As you explore you also start to appreciate the stunning effect whereby distant parts of the city look slightly out of focus compared to the near parts. This is doubtless being done partly for technical reasons, to take the burden off the graphics engine having to show detail over vast viewing distances. But the developers have managed to make the effect so stylish that it looks like a deliberate design choice rather than a technical restriction, and gives rise to some vistas of real beauty.

As with the main gameplay elements, though, although the game delivers the 'big' visuals with outrageous panache, it also loves the little things too. And so we find, for instance, some superbly inventive weather effects to liven the world up (fog is particularly cool), some simply gorgeous lighting conditions, lots of throwaway elements like bits of paper blowing by on the breeze, and perfectly judged use of blurring to give a sense of speed.

Adding to this sense of almost artistic splendour is the fact that all the graphics are delivered with scarcely a single glitch - be it slowdown, distracting pop up, loading pauses or shearing during camera pans.

I guess you could argue that the stylised graphical approach means the picture doesn't look as spectacularly 'HD' as it might have done. Certainly in an ideal world some graphical elements - especially the cars and cut scenes - would have a little more sharpness to them.

But this is a pretty minor niggle versus the scale of Rockstar's achievement in seamlessly rendering a virtual city that actually feels lived in.

Car engines pass from the front of your soundstage to the back in perfect transitions as vehicles glide by, everybody on the street has some smart-arsed remark to chip into one of your speakers as they stroll by, and the sense of space between you and the objects around you created by the subtle manipulation of volume is superb.

On top of this, as we've said already, the voice acting throughout the game is superlative, despite the huge amount of dialogue the game contains, and unlike depressingly many games, the dialogue is hardly ever lost in the mix during a full-tilt action sequence.

Every now and then I couldn't catch everything Little Jacob said to me, perhaps, but rest assured this has more to do with the extreme authenticity of his rich Jamaican accent than any foible with the soundtrack mix.

Impeccably judged, too, is the way the soundstage is able to expand during a meaty shoot-out, giving such scenes added drama.

And then, of course, there's the music. Others keep trying, but nobody else seems able to deliver such a diverse but always cool selection of musical tracks as the GTA games, including this latest iteration. The top tunes available to you ensure that just cruising around town is never less than a pleasure - especially given that even if you get fed up with the music, you can always turn to one of Liberty City's hilarious and brilliantly scripted talk radio channels to help you pass the time instead.

Admittedly real people only enter your version of Liberty City if you enter dedicated online servers and modes; Rockstar hasn't gone quite so far as to make multiple real players share the same environment 'server', as happened to genius effect with Test Drive Unlimited. In other words, you won't bump into real other players while pursuing the single player campaign.

But the moment you first find yourself in a 16-player team deathmatch, witnessing fellow 'humans' charging around Liberty City by the car load, you start to feel as if somehow this multiplayer action is what the whole sandbox gaming idea is really all about.

It's great, too, to see the immense amount of thought Rockstar has put into the wide variety of online game types on offer. Obviously you get your normal Deathmatch and Team Deathmatch options, but there's also:
1. Mafiya Work, where you have to compete to achieve challenges for a Mafia-type boss
2. Car Jack City, where you have to compete to find and steal cars for the same Mafia-esqe boss
3. Race, where you have to, um, race other drivers around various parts of Liberty City
4. GTA Race, which basically means a race with added car-destruction options
* 5. A team version of Mafiya Work
6. A team version of Car Jack City
7. Cops 'n' Crooks, where one team has to help protect a 'boss' figure from the opposing team’s police force.
8. Turf War, where teams fight to control as many parts of the city as possible.
9. Three co-op missions for up to four players: Deal Breaker, Hangman's NOOSE, and Bomb Da Base II.

This all sounds awesome, doesn’t it? Damn shame, then, that GTA IV doesn't fully realise its online potential for two depressing reasons. First and worst, actually getting into an online game can be ridiculously hard. It took 15 attempts - I was counting - before I finally got into my first online game. And this was only a two-person race with me as the host. Yawn.

All my previous attempts ended up in one of two ways: either with me losing the connection with the host before the game could finish loading up (a process which takes way too long for online comfort), or with me being the only player, hosting a game which hardly anyone else joins, no matter how long I wait.

What’s more, this dismal state of affairs occurs no matter what game type I try to play, so it's not merely that some game formats aren't getting any interest.

It's worth remembering here too that GTA IV has sold a simply preposterous amount of copies, so there really should be no issue at all with not being able to find enough players to join you for some online hi-jinks.

One of the problems, I suspect, is the stupid decision to split the online elements into two different areas: Player Games and Ranked games. We've seen with Call of Duty 4 that there's really no need for this sort of artificial division of game lobbies, and here again it seems to be a total and destructive waste of time. After trying unsuccessfully to enter any meaningful Player lobby games, he bottom line appears to be that far, far more people are playing ranked games, and so aside from private parties, it seems to me that this was really the only option that needed to be provided. Especially as all of the game's multiplayer achievements are only earned during ranked games.

Once you've switched to the Ranked game menus and given yourself a slightly better chance of actually being able to get into a game, the actual online experience turns out to be a lot of fun - at least during some game modes.

Cops N Crooks, for instance, can be a blast once you've got to know the maps and have been lucky enough to be thrown into a game populated by mostly quite experienced players. GTA Race is great too, for the sheer spectacle of seeing a real human passenger in the car you're driving chucking a Molotov cocktail at a rival human-driven car. Finally, I really enjoyed all the co-op modes, particularly for the real sense of team-building they produce. I mean, what other game would find you climbing into a helicopter with three other people you've never met before - potentially from four different continents of the world - and flying across Liberty City to a dockside location where three of you will board a boat together while a fourth member climbs a sniping tower nearby? Awesome.

For me the least successful online options are the deathmatches; the still rather ragged shooting system and sprawling, open street layouts just don't make for a satisfying shooter experience, and even after many hours of play I found myself repeatedly dying more because of issues with the control system than actual incompetence on my part. Well, that's my excuse and I'm sticking with it.

It's nice to find most of the games I've played suffering very little in the way of lag, though, and a ranking system built into the GTA IV online experience provides just about enough incentive to keep you coming back for more when you might otherwise call it a day and just focus on the single-player campaign.

That said, this ranking system is hardly on the same level of sophistication as that of Call Of Duty 4 in terms of either its addictiveness or the rewards on offer for advancement.

So where does this rather mixed online bag leave us overall? With an experience that's certainly worth having, but which will probably be abandoned all-too-quickly by many players simply because of how stupidly hard it is to actually get yourself into a decent game.

In fact, so mind-blowing are the game's scale and attention to detail that you actually find yourself deliberately trying to ignore its numerous flaws. And if that isn't a sign of some sort of greatness, I don't know what is.