I have one of these for my Garmin GPS and Slacker G2 radio. Can't say how it compares to other brands since I have only used these. I normally only go for the screen coverage rather than full body coverage.
Definitely prefer this over a gel cover. I had one on an old Palm Treo 650 and it would not fit in the fitted cases or docking station easily. If you're planning on using the car dock or the multimedia station, this would still allow you to use it, whereas the gel case may prevent you from using it or at least make it difficult.