I am looking for a screen protector for my new iPhone. I've heard the one Apple sells at their stores is the PIA-01 iPhone Crystal Film Set. I've used the ClearTouch protectors and like them and see they make one for the iPhone now. My only concern is first, Is it necessary to have a screen protector? Next, do they in any way degrade the performance of the multi-touch screen? Most of all, if I get one what is a good brand to look at?