Eh, it plays it beautifully, Im fine with anything over 30fps on native res and not worth the hassle of booting into windows when I want to play games. I just pray to Cthulhu that Guild Wars 2 gets a native OSX client :3
You'd probably get 60fps in Windows. On my rMBP, some games in OS X run at 45fps in OS X but 55+ in Windows.