Brightness is definitely inconsistent on my Lumia 950 Unlocked. I set it on automatic brightness with 50% brightness. Often when I turn on my phone, the screen is very bright. I check the setting on the Quick Task (notification/whatever it's called) bar and it's set to 50%. Hold down on "Brightness" button and it opens the Settings->Brightness (just a shortcut I discovered that probably everyone knows). I turn off auto brightness and turn it on again, the screen dims. Yesterday, I could not get Auto brightness to stay on until a soft reset.