I run the game on a top-of-the-line iMac in Bootcamp. It runs as well as it would on some other brand's hardware. Perhaps better, as Apple puts some pretty decent hardware in their machines, at least in my experience.

I would really like to play in OS X, though. I hate having to reboot so often, and I can't multitask while playing, as all of my work is on the OS X side.

Also, for what it's worth, I run WoW on the highest possible settings in OS X, and the game runs amazingly well. This iMac is a beast of a machine, I'll tell you what.