As the title says. I didn't even know I received the update until I checked to see what version of Android my Nexus Player has. Absolutely no user interface changes and no new functions.
I thought there was a reboot option
Android 5.1 also pushing to Nexus Player, reboot option available - Android Community
I have the same issue after 5.1 update. No signal from Nexus when TV is rebooted even though Nexus is on.