Other kinds I've used in the past were a thin hard plastic, kind of like a clear overhead sheet, but thinner and sticky on one side. These were not good IMO, because they make the touchscreens less sensitive and since they were hard, the edges would start to peel first and it would be all downhill from there.
The XtremeGuard is a more stretchy film material, kind of like 3M clear bra, or the kind you would find on a car. Its got a nice grippy rubber feel to it, which I actually like. Its "softer" so it sticks better to the screen.
I used a mild soapy water solution to put it on, and at first was kind of concerned with my results. Some areas were cloudy, there were some visible bubbles and when the screen was on it looked all rainbow cuz of the water trapped inside. After a couple days though, all the moisture evaporated, the cloudiness cleared up and all the bubbles were gone. I was left with a perfectly crystal clear screen that adhered all the way around, even on the edges. You would not be able to tell there was a screen protector on here (I have the OEM HTC silicone skin that covers the edges as well so you can't see the edge of the screen protector). The touchscreen works perfectly, and the screen protector does not interfere at all.
The screen protector was the exact size of the screen, perfect cut. Which is good, but makes it challenging to install, if you're off by a tiny bit, the screen protector will stick off the screen and that will be prone to peeling up later on. So take your time during the install to ensure its on there straight and perfectly. I started from the top where the speaker is and lined it up around those lines, and used a credit card to press it down and get as many bubbles out as I could. If this is your first time installing a screen protector, I would suggest getting 2-3 to make sure you get it right. At only $2.50ea, you really can't go wrong here. I'm 100% satisfied.
I would also like to note that I do not work for, or am in any way affiliated with XtremeGuard at all. I simply tried their product, and I liked it, so I'm leaving my feedback here.