
I really cannot wait for more information on this game to be released and I hope they keep up the excellent quality of the voice cast. I agree with one of the previous comments hear in this thread saying about the last game to be using the engine being generally the best in terms of depth. I think this will be the case here. Let's hope for some fresh, new mission types, a new, wider selection of vehicles and of course the brilliant radio stations and comedy that we are used to seeing and hearing in GTA games. 
The engine however was just not ready for todays hardware I felt. By the time GTA5 arrives, hardware will have increased and that engine will be tweaked to hell so it is bound to run a lot better.

the greatest GTA was GTA IV in my opinion, excellent. so good
runs perfectly smooth for me, smooth enough to be able to FRAPS videos and still be able to drive like a mofo. At 1920x1200 no less!