I bought one about a year ago on Amazon just to try it out because I was curious and I wanted to see if there existed something for the PC better than what Microsoft's Xbox pad could offer.
Short answer is, it wasn't very comfortable. I spend a few days trying to configure the "analog" part of the pad but it never moved perfectly horizontal no matter how I tuned it and the analog sticks of the Xbox pad still felt better overall.
I did like the "haptic response", as they called it. The little movement inside when you used it. Nice gimmick, but not worth sacrificing comfortable control and better support for.