Its not worth it TBH.
PS3 version is like other GTA games but San Andreas and Vice City are much better and a lot of more to do in them.
I would say that GTA4 is only around 30% of the gameplay in SA & maybe 50% of VC.
That is the most shocking thing (once you can ignore the graphical issues like blurry backgrounds, low res textures, poor draw distance & sluggish FPS).
GTA4 really needs to come out on the PC as only then can it be all it should be graphically but the gameplay is just poor compared to the other 2 most recent GTA PC games.
Sure it will get a port sooner or later but the gameplay will upset many PC gamers as it is badly dumbed down and the cutscenes are so lengthy, numerous (around 80-100) and poorly acted none are memorable all seem tedious and you would be hard pressed to tell them aaprt as they are nearly all 1-2 characters talking the same old sub goodfellas/sopranos dialogue very few are outside of an interior room.