EVeryone is posting about how well the game performs, but I have a Core i5-750, 7870 "Tahiti LE" and 8 GB RAM and this game still isn't 60 FPS @ Low (everything) details @ 1680x1050. Some scenes hover at 50-55 FPS.
It still looks fine (excellent, in fact), but having to use Low on a very decent system is quite ridiculous.
Setting everything to Medium makes the average frame rate around 30 FPS.
This review says you should be getting around 47fps on High settings. It is quite a demanding game but based on the comparison screenshots even on Low settings it looks quite good.