I bought a set as a Christmas gift for my pre-school daughter. Good first impression, works fine, the app seems quite good (but the train is usable without it), the color "programming" works nicely and is quite funny to watch a train going on its own, stopping on stops, reversing track, etc. I'd like to have a slower speed (the train offers three speeds but even the slowest one is quite fast, IMHO), though. (And the guide states the train detects derailing and stops automatically, which it doesn't in our experience, it just goes on on the floor...) Now, I'm thinking about reverse-engineering the BT communication and building my own app... :-)