I've used the Shield screen protector products before on a couple of cellphones and here are my observations:

1) Giant pain in the butt to put on, what with spraying the soap solution and the hellish time of trying to avoid bubbles, real nightmare.

2) The screen protector is not scratch proof. I tried their little key trick on my old smt5600 cellphone and had permanent marks on the protector. Sure the phone screen was fine, but the divots in the protector were not fun too look at.

3) Absurdly overpriced. Bestskinsever.com sell the exact same product for about 1/5 the price though I don't think they have them for Nxxx products.

4) Switched to silicon based protectors (screenpatronus on ebay is great), which use a silicon layer instead of an adhesive to attach (try pulling of a shieldzone product after a few weeks....holy crap its hard to get off, and the mess it leaves on the screen...). Got 3 for ~$11 and they go on super easy, no bubbles, can be removed and washed, and the work great with a touchscreen.

Almost forgot. It's no longer shieldzone, but zagg for the overpriced annoying to apply screen protectors (if you really enjoy pain and suffering)