Okay so this topic might have been brought up before. Worried that the white navigation buttons which is constantly being displayed at the bottom will burn in quickly. Once AMOLED screens burn in, it's over and non-fixable. If you're owning this phone for over a year, it might burn in eventually. I've never experienced burn in on any of my Galaxy phones in the past because I'm careful not to leave the screen on too long (turn off the screen when using Google maps). But now that the navigation buttons are displayed on screen, there's a chance.
Any long time Nexus 6 or 6P owners can comment? (Owned for at least a year)
Example of screen burn in: