I've operated with PDA's since the first Palm and have never used screen protectors. Scratches rarely built up thru the myriad of devices I have/had.But yesterday I found why I need them. Greasy fingers.

I had always made it a point to keep my hands & fingers clean before touching a screen. Well yesterday, to my dismay, I handed my 810 to a friend and he proceeded to "grease it".

So thanks to this thread I pulled out a sheet of OH transparency film, trimmed it (not accurately) so it was just a little to large to fit inside the bezel, slipped it in and voila instant protection.

To note:
Stylii and thumb response seem about the same, before it would take me a couple of taps or so to get the "thumb board" up in notes. It still does. Which is great because I've been a thumb typer since my HP 95 days.

Though my vikuiti is unscratched, I can clearly see a difference where the stylus has been used most of the time (on the right scroll bar and on the virtual keyboard), and that's after less than 2 months of use.
Cleaning it energically will remove the spots for a while, but they're back in no time.
Maybe because of the piss-poor performance of the touch screen (especially when you're trying to right click a link in microb) I'm going too hard on it.