Bought GTA4 on Steam last night and started giving it a whirl. Had it on the 360 when we moved house (no net for 6 months) and really got into it then!
Was reluctant to get it on the PC after all this gafuffle about it running poorly etc. Loaded it up last night and it ran fine with the settings I was using, so really don't know where all the issues came from to begin with...
But back to the topic, this would certainly be on my "buy" list. Owned every single GTA game (minus the Episodes) and loved every single one of them. Setting won't bother me, but would love to have the depth in it like GTA:SA - there was so much to do it was brilliant! Don't think I've ever found a game with so much re-playability.