I've been tinkering with 9.10 for the last 3 days. So far I haven't experienced any show stoppers and its very stable. I think the stability in this release can be credited to Debian Unstable which seems to be rock solid although its supposed to be bleeding edge. I still don't like the way sudo is used in Ubuntu, so I hacked the distro and reverted to the classic model so all the apps ask for the root password instead of mine.