I'm starting to collect a list of problems that I can confirm happen on more than one computer:
1. Suspend doesn't work anymore. Come on! Really? I thought we left this crap behind many years ago. Suspend the box - then wake it up and things are just... wonky - crashy - unuseable. Have to reboot to fix. So I shut the boxes down and reboot instead. Annoying.
2. When I upgraded there was no top panel clock. I Googled and found how to put one with CLI. It was fine for a couple days. Today I look up to see what time it is and... no clock. WTF? Why did it go away? (Hmm... This might be only on my main machine. Haven't confirmed it on a second box. Could be because of upgrade instead of fresh install.) EDIT: After another restart it's back.
There are more, but I don't have them memorized yet. I'll have to start taking notes when strangeness happens. Some are just annoyances, like Nautilus being ruined, and Nemo being very good but not quite ready yet. Or Palimpsest being castrated of most of its useful features (not Ubuntu's fault, but still annoying).