If you do a search, you should find a lot of threads on this site and others. DD'S hitting coach likes it a lot now that he's figured out how to use it correctly and it has helped out showing DD her bat path etc...
I've had one for almost a year. They have made several improvements and updates to the user interface since I bought it. It does a really good job giving a ton of information. I also like that you can track and compare multiple users ( one of the improvements made from the original app). I really like the 3d swing tracker. It gives a great look at overall swing and bat path. In my opinion if you are a techy gadget person , this is a good one for your collection.
If you do a search, you should find a lot of threads on this site and others. DD'S hitting coach likes it a lot now that he's figured out how to use it correctly and it has helped out showing DD her bat path etc...