I just finished the story and will never, ever 100% this thing. It's too much of a pain in the ass to get where you're going without driving all over the fucking place, and I'm just over it, even though it's nice to see L.A. again (especially without traffic). I just wanted to jam myself through it all before the online mode went live.
GTAV was a million times more interesting from a story perspective than GTAIV, in my opinion. I stopped GTAIV because I just couldn't have cared less about the boring characters.... since then I've completed Max Payne 3, Red Dead Redemption and L.A. Noire... so Rock Star has won me over. I may go back and try to stomach GTA IV again, but I doubt it with PS4 coming in a month.