I have no direct experience with Windows 8 under Boot Camp (didn't want to interfere with my W7 partition) so I ran it under VirtualBox.
However, I've heard and seen people have problems. Mainly with trackpads not working properly, but also some of the Function keys along the top (keypad brightness, volume etc.) don't work apparently. Apple really need to update Boot Camp to support Windows 8 - but I suppose it's a bit early days for that at the moment.