The beta ran really smoothly for me with a medium end rig that is pretty old now:
i5 750 oc to 3.6GHZ (when turbo kicks in, it goes to 3.8GHz)
8GB RAM oc to 1520 mhz iirc
MSI 7850 OC 2GB
1080P res
W7
And that was with high settings (AA turned of [will be using a sweetfx config], no ambient occlusion and no AA post) and mesh set to ultra. IIRC average FPS was around 50-60 with minimum FPS going to 35.
I expect the performance to be even better for the final version too if any of the recent high end games are to go by i.e. bf 3, crysis 3 etc.
Saying that, come the final game for multiplayer, I will probably play with mostly low/medium settings as I want a consistent smooth experience in the big action battles!
The only problem I had with the beta was crashes every 2-3 games and bad stutter every now and then at the beginning (not as bad as what other people had but the patch completely eliminated that for me)
The only thing which I need is a new keyboard

can't decide between the corsair raptor k30 or the cm storm quickfire rapid TK red switches........