Oh. My. God
It's so... Fun
I barely spent any time with the story and just exploring, forget anyone who hates it just for it's Graphics.
What part are you at right now? I mean, the whole game's great, but to be honest the LS area is the best area because of its diversity and the driving space. SF was the last to be created, so it's kind of stuffty and very boring; and then of course, there's Las Venturas, which is just as boring but has better cop cars.