I've been noticing a couple of things with Win8 compatibility and wanted to note it here for discussion.
I've noticed that we have a lot of problems (at work) with Win8 being installed on older systems. And the issues seem less when using updated BIOS's. Nothing scientific here, but I now update the BIOS on every system that I update to Win8 (I don't do "upgrade" installs - all of mine are "clean" installs). I've probably done 40 or 50 installs since Win8 came out - and the last 5 (edited from 10) or so have all had BIOS updates.
Also, I'm noticing BSOD problems (mostly STOP 0x133) when using an additional audio card. I suspect it's USB/external audio - but haven't seen enough to nail this down. Also, there has to be a video card with audio capabilities (and drivers) involved. What I usually see is outdated drivers for the USB/External card and fully updated drivers for the audio on the video card. I don't recall enough to describe any symptoms because I just started to notice this.