I have one that my friend who owns a tack store gave me to try out. To be honest, I wasn't impressed.
The pad started wear very quickly and I didn't like how the gel would bunch up in some areas and thin out in others. It never really went back to it's original shape, and since I use it on multiple horses with multiple saddles, I like a pad to conform to what's it being used with, not just one saddle and horse. Had I paid for it, I would have been upset.
And, you don't want to leave it where it can freeze, which is an issue where I live.