I have used the invisible shield on several devices including cell phones, Palms, GPSr's, and my Pearl and Curve.

I don't find the installation difficult, but you do have to pay attention to what you are doing when installing them, both so that they are applied straight, and so that there are minimal bubbles.

My main issues with Shield Zone, is their customer service responses, price compared to comparable products(ie BSE), and that despite being "designed" for a product, the cut outs do not always fit correctly.

--Coyot21