I do regret upgrading. My wireless trackball and mice no longer work smoothly and this is a known problem apparently with RF and bluetooth pointing devices. It's one thing to make things slower or for new features to be buggy, but making the system unusable is unacceptable, IMO. I'm looking at dual booting Linux now and possibly making the switch back. The only reason I haven't yet is because I luckily still have wired versions of the same trackball.