Always expect "issues" when updating, make a <bootable> backup of your working install with CCC or SuperDuper! before trying to upgrade. Boot from your backup, download the upgrade package install it on your "working install". Delete AppleIntelPowermanagement.kext before trying to reboot with the working install - if you do not - you will get a KernelPanic (99% sure).
Expect that sleep is not working anymore and to apply most patches again.
Cheers, I'll give that a go when I get the chance