I woke to find the OTA 5.1 notification waiting on my N7. Downloaded, installed and let it 'optimize' the existing apps. It rebooted, I went into the Store and found a number of updates to my apps waiting. Did those. Used Ccleaner to do a tidy and then did a hard reboot.
Back up and running and everything seems fine so far - not sure if I'm seeing any speed or stability improvements over 5.0.2, or just willing it to be so.
If there is a worrying caveat, it's that I looked at the possibility of doing a Factory Reset just to make it as clean an install as possible, but there was no option to do it and restore all my apps from Backup at the same time, as was the case with 5.0.2. Hmm. Gave it a pass and will hope everything works out.