I had phantomskinz screen protector. It is a nice product, but, I felt like it was a bit too grippy on the touch screen for me - so now I have nothing on the screen. It did not effect the responsiveness of the screen, which was certainly very nice.
I bought the 3 pack of screen protector films from the VZW store a few days after getting my Droid. It paid for itself tonight, when I dropped my phone... There's a slight scratch, but only on the film, NOT on the Droid's screen . The film hasn't had an effect of the touch screen at all so, better safe than sorry . Plus now, I don't have to cry!
My phantomskinz screen protector has scratches and dings all over it and my Droid is the only thing in my left pocket. Hopefully yours turns out to be more durable because I'm very disappointed with mine.