After upgrading it blew away my .htaccess file in my public_html folder. In my case I would have preferred to have done an uninstall then a fresh install.
"50,000 customers can't be wrong!" It just didn't work for us.
Tech support was good, though. Except support incorrectly told me my site's been down for a week (it wasn't, he was looking at a corrupt Google cache file), and a moderator challenged me on the fact that my install failed.
Based on a previous version's log file, our site is getting hammered with all sorts of bad guys. So I guess it's doing its job.
I'm a bit of a novice though so I guess everyone including me was having a bad day.