I used the InvisibleShield on the n800.

Pros

- It will protect your device, it doesn't get scratched or damaged easily
- Somewhat easy to apply with the materials and directions they provide you
- It lasts a long time

Cons

- The fact that it was developed for the military as they advertise shows.. the thing is thick and reduces touchscreen sensitivity. It's hard to draw with the stylus

- It gets dirty easily and is slightly difficult to clean
- Feels rubbery when you touch it


I am currently looking at Durasec screen protectors (if anyone has any information about them like reduction in touch screen sensitivity or rubbery feel that would be appreciated). I'm going buy a hard shell for the n900 and a screen protector.