I have been using the product. I'm not really happy with it, especially the app. I was hoping for some features that would help me improve my game, such as specific suggestions on what shot to play more, some specific movements or exercises to improve speed of shot etc. I also had issues once or twice with sync and also it seems to be lacking a notification for low battery.
Pros - doesn't interfere with your game at all. Before buying was worried about the device falling off but the silicone holder is a genius design and does its job fantastically