I've tried to enjoy GTA 4. I've loaded it up several times, I've gotten through a few missions, but I just get bored and frustrated with it before too long. There are several reasons for this:
First there's the fact that walking,.running or driving, getting around is really, really slow. Or at least, it feels that way. Even when you're driving fast, you still don't get any impression of great speed, and you start crashing into everything.
Then there's the issue of character motivation. I have tons of money and no apparent reason to be falling in with these criminals beyond the little bit needed to get Roman out of trouble, but I'm doing it because that's all you can do in this game.
But the main reason I can't get into this game is Niko fucking Bellic, the awkwardest, most off-putting protagonist ever.