It's rare but every now and then testing has an unsatisfiable dependency. It's usually resolved within a day or so. But I keep a lower distro around basically to insure I have a fallback, so I'm not blocked now. The next update should likely get me back to testing.

I run sid (debian's unstable branch) on all my systems, it's great! With experimental pinned on at low priority! It's great, I love it!

I'm not quite bold enough to recommend it to people but if anyone asks I would definitely say yes to running sid. Apt-pin for testing at low priority is good to have, just because sometimes there's lag when one library updates for everyone using it to update, and you can get unsatisfiable dependencies.