I was originally going to pass on GTA:O, but I got a free month of Live, so I gave it a try. The first week was rough, I only tried twice throughout that first week and then didn't bother.
After a few patches, I tried again a few days ago, and having a blast. It really helps to play with a crew/friends instead of random people who will do nohing but try and kill you.
The racing is a lot of fun with crew/friends who won't be *******s and ram you off the road and whatnot.
My main complaints are:
1) Can't buy grenades until level 15+, but there are missions that have you destroy vehicles/planes. That's annoying.
2) The NPCs seem to all be eagle eyed snipers. Can't tell you how many times I've been headshotted by a thug with a SMG at extreme range.