After one install on older machine it worked well but unity-system compositor would cause flashing and flikerty. I was able to restore back to X by removing unity-system-comp..
I then tried a nomodeset install and got a VESA dirver (unlike the first which was a Gallium) Now it is like molasses. This of course is a regression of the hard-installation process because I have suacy on another hdd on the same machine that works great with unity system-comp, ccsm and is very fast.
It's like the jockeying process does not know what it is doing (again). Have not tried it on my power machines as of yet but it is otherwise very stable in "live" session mode and installs solidly so far.