I always check my power level, and today it was suddenly drained. Doesn't even register that it is charging when I plugged it in. Good thing I don't really depend on any phone, since I'm retired and nobody but spammers call me. :) I'm sure they'll fix this, but I hope the phone is in a condition to receive the fix. :(
My old Nexus 7 got the update, and so far it is holding.
Update: I'm thinking now that the battery may have been drained by a flurry of updates. It seems to have settled down now, and is charging normally. My advice is to keep it plugged in a lot after the update.
Update2: It is still weird. Today it refused to turn on by pressing the button. I had to do a power - vol down thing to restart it. The battery was at 56%
Update3: I just did the factory reset which they now recommend. Many people have had problems and this apparently fixes everything.
Update4: This has cleared all problems and the battery life is good now.