About screen protectors: I scratched my first 3DS pretty badly from playing Kid Icarus (a horizontal, pretty deep slice in the middle of the screen since you constantly have to readjust the camera in that game). I applied a screen protector but it looked awful, bubbles were hard to get rid of but worse, the touchscreen became a lot less responsive. I had to apply a lot more pressure for Kid Icarus to even notice I was swiping. So I took it off again |:
I now have a new 3DS (the first one had motherboard issues so I sent it in for repairs) and I've been playing Theatrhythm pretty manically without a screen protector. Yet the screen is still not scratched. I think it's because I now use a third-party DSi XL stylus. The tip is bigger and made out of plastic, it's a lot less sharp than the regular 3DS stylus.
But I guess I'm still going to trade it in for the 3DS XL, because the hinges of my regular 3DS are kind of loose, so the top screen flaps around when I move the system while playing... plus my HUEG hands could really use the added size for comfortable play.