Installed a few days ago (got it a bit "early" shall we say). Did an Archive and Instal, no issues with the instal at all.
Booted up and all my settings were there, it hopped on my wireless network PDQ. Almost none of my UNSANITY Haxies worked, but UNSANITY upgraded them all a day ago so they all work again (Bless them!). My MS Mouse software installs, but not all of the Trackball settings are working. I have buttons programed but they don't work as programed. The system could not figure out my Keyboard and the Logitech Control Center software errors out when I try to install it so I have had to switch keyboards until Logitech gets on the ball and fixes the problem.
Spotlight - Meh, way over-hyped, FIND is still better.
Dashboard - Sucks, Konfab is still better
Mail - NICE!
Safari RSS - Why do I want to use my browser as an RSS reader?
Automater - No easier to use than Applescript ever was.
Overall a WAY over-hyped upgrade that is NOT worth $129....