I saw strange auto-light adjust behavior last night like Sir Loyne reprted in this
thread.
Twice, I was reading in a dark bedroom, and the light went to 0. Another time, I bumped it back up to 11% and watched it auto-adjust up to 100%!
I finally turned off the auto-light adjust.
I also noticed my battery life was terrible. I didn't read for anywhere near 15 hours yesterday, but I went from a full charge before applying the update to under 10% when I went to bed last night. This morning, I am charging it back up.