Another Zagg IS user here - well, kind of.

I put on an Invisible Shield on Day 1, and a couple of days later, I had to exchange the phone (defective headphone jack).

I ordered a replacement from Zagg, but it still hasn't got here after about 2 weeks, and so all this time, I've been rocking it naked.

The screen is holding up pretty well - there's just one hairline scratch, needs the right light to be seen - but as soon as the IS gets here, I'm putting it on.

It does make the screen less slippery at first, but you don't actually need to press any harder with it on, and the protection is phenomenal.It even molds into and hides existing scratches!