As GTA IV proved, graphics alone does not make a good game. Compare GTA IV to Vice City - in my opinion IV is just showmanship by comparison. Vice City has so many elements at play, most notably the whole 80's scene which was done perfectly. San Andreas is 6 times bigger than GTA III and Vice City put together and yet, like GTA IV, it's a game looking for an identify. The only thing that saved San Andreas - a game never designed for multi-player - was the gaming community's efforts in adding a multi-player element. GTA III and Vice City had this feature bolted on (still being worked on), but it didn't need multi-player to be good. The storyline, concept and execution were good enough to keep you engrossed.
Make the game original and nostalgic. Make it open. Make it playable. Make it customizable. Make it so that you can pick it up and do what you like. You don't need 6 cores and 4 graphics cards to do that. I just tire of games trying to out-do each other in terms of technicality rather than originality. What did you like about GTA III when it came out, on PS2 and PC? Bring that back, because I think it's been lost..
This game has to draw it's inspiration from somewhere. It's just that after the 70's and 80's.. well you know the rest.