As for bug fixes, there's quite a few for me:
Smart stay is improved. The eye icon stays in the notification bar longer so I think it has a more thorough check to see if you're looking at the screen.
Less wakelocks, so battery is vastly improved. At least it appears so.. if my battery dies at 19% or something I'll be annoyed
Home screen refresh happens much less frequently.
I can switch between the 2.4GHz and 5GHz bands on my router without having to turn WiFi off and on again.
Pretty awesome update!