Yeah, people don't remember just hwo awfult he console verison ran and looked.
The LOD levels were SUPER low as well, thigns just dissapered half a block away on occasion.
The PC verison was a poor performer, but it was still leagues better than the console version.
I'm confident GTA 5 on PC will run much, much better than 4 when it released. DX9 wasn't very good at multithreading, and if memory serves the PS3 team ported the game to PC.
Rumor has the team responsible for MP3 is working on GTA 5 PC.
It won't run at 60fps on an Intel 4600 so I guess in the eyes of some it won't be well optimized. :]
The question I've been asking myself is what architecture will the game favor, GCN or Kepler/Maxwell ?