For me, BS2 runs badly at about 20fps with Crossfire on, but with Crossfire off it is 28 to 32fps, I have to have detail at medium but it is reasonably smooth, would be good to get more fps, but it is probably my slower cpu (AMD Phenom 9600 quad 2.3) rather than the gpu.
BUT I am also running Eyefinity 3 monitors so it's pretty good considering that :)