you'll almost assuredly leave bubbles or dust underneath the front polarizer when you install it, as its adhesive backed.  its like trying to install a scratch protector on a cell phone or something...  but the material isn't as friendly.  those are the issues i've had at least.

Alright, so I got a Gameboy recently that didn't have the screen cover on it and the front film has a few small scratches in it. I'm curious on 2 things. 1. How bad would these look once a backlight has been installed, would it be VERY noticeable? 2. How hard is it to replace the front polarized film? I know that it can be a real pain to replace this film, and a few things I read is it will never look the same, but I haven't seen any tutorials or after pics on it to show just how bad it is. If anyone can shed some light on this for me, or even a pic of a backlit screen with either scratches on the film or a replaced film all together I'd be very grateful.