I gotta tell you, after reading about the power support shields (after I had already ordered the ZAGG) I am leaning towards keeping the zagg. Yes, there is a "rubbery" feeling to it, but I don't find it to be bad for using the touch screen at all. What I love about it is how grippy the phone becomes, which to me seems like it will reduce the chance of the thing slipping out of my hand.
When I first got the phone a little over a week ago, I had to rock it naked because I am too cheap to buy a case when a free one is coming. So I just kept the factory plastic pieces on the phone for the week (I cut the tabs off the bottom) which made it hard to hear the other person on the phone. The zagg came in yesterday and I installed it. No bubbles, no imperfections or anything. Yes there is an orange peel look to it, but to me it doesn't affect the screen performance or anything.
In fact, I am so happy with it so far that I am considering just selling my free case and keeping the IP4 with only the Zagg skin. My only concern now is longevity - if the corners start to peel or what not then it will have to go, but it has only been about 18 hours so far... We'll see.