I'll never understand screen protector users. Our phone has Guerrilla Glass, designed so you DON'T need a screen protector, and it works. I've never had a screen protector on my Ace, or any of my phones for that matter, and none of my screens have scratches or marks.
My Ace Screen looks like it just came out of the box, and it has been dropped, and I have even tested the durability of the screen by trying to scratch it with a knife, keys, and sand paper... and it still looks brand new.
Screen protectors make the phone screen feel less slick and smooth, and they are difficult to put on and remove without air bubbles all while staying centered. You can't even force out most air bubbles with a credit card or flat edge. They also make the screen less responsive, although this isn't much of an issue with capacitive touch screens anymore, it still happens if your protector is too thick.
What are you doing that you need a protector? I carry my keys and stuff in one pocket and my phone in the other, and even if they are in the same pocket, none of my phones have ever been scratched by anything in my pocket...