I still use my original PRS-500 (2006?) - haven't noticed any change in the screen, still great. I replaced the battery back in early 2010 and it maintains a charge like new again. It's been handed around to different family members, until they buy a reader of their own (usually kindles), and back comes the PRS-500. Someday it will be a extremely valuable classic collectors item e-reader,
or maybe not...