Here is my Zagg review.. Everybody has an opinion right?
People hate the 'orange peel' feel of the Zagg products. On something like a blackberry phone its not as noticeable. But if you put on large touch screen display its ugly. The material they use also has a more 'rubbery' feel to it then other products. It has a tendancy to grip/stick to things if your put your device face down (magazines, books.. etc)
Over time the Zagg screens turn yellow... It seems to take about a year but it happens. I've also found that after a few years the material isn't as strong. I did the 'pen test' with a 2 year old screen and it ripped through it like it was paper.
Having said all that... I live in the land of Zagg (Salt Lake City... home of Zaggs corporate office) and service is always great. You won't find a better install job then the ones done at the corporate office store.
Luckily there is another company in town that designs/sells screen protectors also labeled 'developed for military helicopters'. Their product has a super smooth finish and is thinner then Zagg's invisibleSHIELD. The cost is about the same... but after seeing how scratched up my iPad 1 screen got without protection i thought i'd try it on my new iPad 2. Most people cant even tell i have anything on the screen.