I had not intended to go to the store to get this specifically - but happened to notice it in passing. The idea of having a ball-joint mount seemed so obvious, how has it taken GoPro this long to think of this?!
Overall, it's good, but it could be improved. The joint itself is a bit stiff, which is both positive and negative; it prevents the camera from slowly drooping back toward the earth but it also is much more stiff than it needs to be. When I first got it, I expected it to easily rotate, but it resisted. In fact, it resisted enough that I had to take a close look at it, with a thought that maybe somehow they managed to package the wrong product in the ball joint packaging. After a bit of muscle it did finally turn, and bit more muscle it turned again, and now just requires a little muscle to turn as needed...but that little bit is a bit more than I would expected (a small child probably could rotate it...that...or I am just stupid weak)