First off, I'm a big fan of Grand Theft Auto games, particularly Grand Theft Auto IV. It's a great game, definitely the best of the current generation in my opinion, most likely the best game in the past 5-10 years. I feel that it's definitely deserving of ratings of 9.8-10. I do not, however, believe that the game is perfect. Why then should it get 10 you ask? Because no game will ever be “perfect”, because better features, gameplay or graphics will eventually best them. But to get 10/10, a game doesn't need to be perfect, it simply needs to be a game that is truly phenomenal and that pushes gaming that bit closer to “perfection”. Grand Theft Auto IV is one of those games.
Now down to the flaws in the game.
Excessive Load Times
Liberty City is phenomenally detailed and extremely big, but that doesn't quite compensate for the time that the game takes to load. I'll admit that consoles now load far quicker than older consoles, meaning that the effective load time of a game is less than it was 10 years ago. That is of little use or advantage though when a game takes 1-2 minutes to load. There are only so many times you can see the loading pictures before you think to yourself “what the hell am I doing with my life?”
Unfortunately, when you die, you also have to wait for the game to load, and you can't pause the game quickly and load a previously saved checkpoint. This means that you can't quickly restart when you die. You must wait until you come back alive at a hospital, and then load your previous checkpoint.
Mobile Phone During Battles
The Mobile Phone in Grand Theft Auto IV is generally pretty phone to use, especially for calling in backup or getting weapons and bombs, but why the hell does Niko answer his phone when he's in a fight? He's shooting people or cops and they're shooting him, but he answers his phone if someone calls him? That's just plain idiotic. Especially considering you can't use weapons or steal cars or bikes while you're on the phone. You just get shot to pieces while you're telling Roman that now isn't a good time to go bowling.
Multiplayer
The multiplayer in Grand Theft Auto IV is great, don't get me wrong. Infact, it's quite amazing and is just what the series needed. That's once you're actually in the multiplayer. It takes 30+ seconds to load, and then it tells you that the connection has been lost. Then you wait another 10-30 seconds to be returned to single player where you try again to enter a match. Then when you're waiting in the lobby, there is no way to occupy yourself before the match starts. You can't look at your/your friend's stats. Luckily you can listen to the radio stations, which leaves you somewhere between indifferent and moderately occupied.
There are some other small little flaws, like occasional glitches with the physics engine. On the whole though, the engine works pretty well. There are also some problems with no checkpoints during long missions. While you may be sad/angry they're missing, you'd probably find the game to be far too simple and quick to complete if they were present.
All in all, this is still a game I feel deserves all the great ratings that it has gotten. The last time I played a game this entertaining and classic was when I sat playing Goldeneye on the N64 back in the late 90s. This is a must-buy, must-own game which I'd give a rating of 10 (out of 10) to.