Thus far, I've only noticed a few differences:

a) wakeup is noticeably faster.
b) you can now browse stacks.
c) that hideous blue glow added to Exposé!

At first I thought this was a bug, so I started looking for a fix. It seems however, that Apple did this on purpose...

If I never used Exposé, I probably woudln't care, but I use it all the time! I couldn't stand seeing that obnoxious "MS Paint" boarder every time I switched windows. So I fixed it...

The process reminded me a bit of hacking Windows Vista to run on my first "Vista-ready" machine - one of the reasons I switched to Mac. While this won't cause me to switch back to PC, it is a bit annoying. Overall, Apple releases really good products, they pay attention to the details, and they get it right the first time. With the number of complaints out there, I don't doubt that one of their first major updates will resolve this. Just wish I didn't have to in the mean time.

If you're annoyed by the Glowing MS Paint in Exposé, it's super easy to fix:

a) Go to, MacintoshHD > System > Library > CoreServices > Dock
b) Right-click and "Show Package Contents"
c) Locate and delete "expose-window-selection-big.png" and "expose-window-selection-small.png" (replacing will give you an error, so you have to delete)
d) Copy these .png files to the same location.
e) Open the Terminal and type, "killall Dock" (Case sensitive).

The result: