I got a message that the OTA update to Lollipop was available for my Nexus 7 so I installed it.
It made the tablet unusable. Performance was atrocious, battery life could dropped to a couple hours. It couldn't play music. Doing anything took so long (if it worked at all) that it was really not worth it.
I googled around. One suggestion was to clear the cache. I tried to do that but when I tried to boot into recovery that always failed with an error about "No command found."