[amcintyre]

My personal reason is that it felt like beta-quality software at best. The UI would hang almost every time I tried to log out, for example, forcing me to go to a tty to kill the lightdm service. As lysol says, it seems like things that used to take a mouse click or two now required a lot more effort (but I'm willing to admit I probably didn't try hard enough to figure out the "new way" to do them).

Beyond the UI, stuff that "just worked" before (like my wireless network adapter) now didn't work at all without manual intervention.

All told, it was just too much hassle on a machine where I just want to get some work done. Yes, I should probably know better than to upgrade a Linux distribution on a machine that I use to actually get some work done, and it will probably be a while before I upgrade again--I'll just choose something usable and leave it alone until I have a week of vacation to spend fussing with updates.