Fairly well imo. We own one and used it for about 6 weeks last winter. There are some bugs with it that is annoying (like measuring the spin rate and other things on every other throw as my son and I were measuring his pitches that I was catching and throwing back). The mph seemed fairly accurate compared to the pocket radar. It does require a subscription after the first 2 weeks. Cannot recall the monthly cost that is billed thru iTunes or google app-store.
Son not pitching anymore so it is a $99 paperweight on the shelf for now.