Same here, donwloaded the update then a blue screen on the reboot message saying 'a device required is not available', it doesnt mention which device/driver.
All drivers up to date, ran a chkdsk and sfc, tried the installation 4 times now. Im running a Macbook Air with Intel HD4000 graphics, maybe its a problem with a driver somewhere, I dont know but I was quite liking Windows 8, infact I have stopped using OSX, but this issue is reminding me that things just work with OSX, Windows can be such a pain to say the least!
Come on, any ideas Microsoft?