Count me in as another long-time Opera user who uninstalled Opera 15.
After reading this thread, I do resent the fact that when I went to get a copy of Opera to install on a newly set up Win 7 x64 machine, the website gave me Opera 15 without any warning that it's still a beta. I don't do betas any more -- haven't the time or the interest in dealing with the problems that sometimes come with them -- including missing features.
In my case, I was upgrading from Win XP Pro. That means a clean install. So of course the Opera 15 install didn't find any Opera 12 files to import. And the folder structures have changed, making it hard to figure out what to do with the config files from my old setup. Then I discovered some of the missing features -- especially the site preferences for things like javascript, plugins, etc. That was enough for me. I uninstalled Opera 15, installed a copy of Opera 12.16 from Opera's website, and copied the config files into place from my backup of the old system. Everything seems to be OK. Whew. But all that blew away a whole afternoon in which I could have been installing other software or enjoying the sunshine.
Thank you, Opera, for at least making the configuration issue fairly simple in Opera 12. I really didn't want to lose all my bookmarks and passwords. The bookmarks and Speed Dial came across from Opera Link OK, but not the passwords or site preferences. And I don't know what else didn't come across; that was enough for me. I just overwrote what was in the config files with the files from the old system.