In gta4 you play a Russian immigrant called Nico. After arriving you start to help your cousin out with his cab service. During the first few missions you find out your cousin has debts with some criminals. after some more missions you kill them and because of that you made some people higher up the ladder a bit mad. The story escalates from this to you being part of several organized crimes. Nico also has more reasons why he went to liberty city but we won't tell that here.
The Graphics are very good, everything is done in great detail and there is not a single place in the game completely forgotten. Also the physics in the game are really good, even people have ragdolls with physics and real responses.
Game play wise it is really good, the missions can be a bit repetitive but never too much to really bother you, there is one thing that will bother you tough. The driving, it as if the roads are made of ice, that and the insane suspension gives you one hell of a ride
the multiplayer is reasonably fun. but it can end up in complete chaos considering you are still able to reach the whole city all the time, only the pedestrians and the police have been removed.
In the end it is a pretty good game, that even with the downside puts up a good multi player and an even better single player