Tried installing +SteamOS
yesterday using their UEFI zip image. I have to say that the installation felt maybe a little more uncooked than what I would have expected from something called a Beta. Spent about 3-4 hours on it and I still don't have a working install. First weird thing that happened was that I had to mount my USB drive as a /dev/cdrom during installation (solution found on a SteamOS forum). Once that was done installation seemed to sort of complete, but in the end when I reboot I just get a black screen. If I try to reboot into safe mode I do get a console prompt and looking at the installation I have to say it looks broken, the sources.list file for instance points to the install DVD and I can't for the life of me get an X Session started.
Will try again at the next release, hopefully they will get these things cleaned up as we are rapidly are heading towards the November launch.