here is my opinion about GTA 4:

User Rating: 9.5 | Grand Theft Auto IV PS3
first of all i want to recommend this game to anyone who likes action/shooter games. gta 4 is worth every single dollar because it is so long that u'll probably need 40 or more hours to complete the single player mode. average game today requires about 15 hours to complete and if u look at gta's 40 you'll know what i'm talking about.

GRAPHICS: are pretty good but not like mgs4 or RE 5. my score for graphics is 8.5/10.

STORY: only thing that i can say about story is woooow.... great story one of the best these days. my score 9.5/10

GAMEPLAY: is same as previous gtas with few improvements like u r able to crouch, take cover and now u have a mobile phone. my score 9/10

CONTROLS: they'll require some getting used to but anyone who says it's easier to play it with keyboard and mouse is wrong. score 10/10

LASTING APPEAL: after completing story there's a lot of extras like chasing bad guys in liberty city, stealing cars, getting all the trophies and many more. score 10/10

OVERALL: GTA 4 is outstanding game that'll keep u coming for more and more... it has great multyplayer and it almost can't be boring.
i recommend it. buy it.