Indescribable. A true masterpiece by Rockstar.
That's pretty much what I love best about GTAIV, but almost everything is perfect. There is so much to do in this game. Even if you beat it, you still want to play it again and take the different paths laid out in the game... My favorite additions, (apart from non-cartoon vehicle handling and the amazing graphics) are the ability to hang out with friends, hide behind stuff, the ability to switch targets (You supposedly could in San Andreas, but I can't seem to), and the variety in cars, pedestrians, and missions.
Rockstar has done it again, wowing us (or at least me) with a new masterpiece that push expectations of what the perfect video game should be. So far, in my book, Grand Theft Auto IV has that title. The characters are hilarious, and many times, have a story behind them.
If there were anything I could change about this game, It would be the monochromatic environment. By that I mean, unlike San Andreas, there is, for the most part, only one terrain type, and that is city. Not that I don't love Liberty City, or that I believe a console is capable of having graphics as amazing as in GTA4 and at the same time having a massive environment, it's just that f you can't find anything to do (which is pretty hard) the game can feel stale. If there could ever be a game as graphically...amazing.... as GTA4, have the variety in vehicles, peds, and missions, and the same increcible gameplay, yet have the same massive and varied environment as San Andreas, that game would most likely win the best game of all time.
So apart from the lack of terrain variety, and the strange appearances of vehicles of the same kind you are driving parked on the side of the road, This game is PERFECT.