I updgraded from F10 to F12 a couple of days ago. It was easy and painless*. Thanks all for producing such a wonderful distro. I remember back in the bad old days when you had to take a leap of faith to attempt an upgrade, and you'd end up reinstalling from scratch anyway.
* Aside from the scim -> iBus upgrade, that is. After I got that worked out, it was flawless.