I've been using this app and running some tests for some time now. I posted a run through of it's abilities but would like to add my two cents as well.
The tracking feature is the best of all the apps I've tried (I've tested all of the Android apps). It allows a person to get shots that they normally not be able to get if they needed to fly and control the camera at the same time.
Two changes I'd make to the app.. on a small note I'd default the telemetry to an "on" state with the option to turn it off. On a much better note the app needs the option to turn off return to home when the connection with he controller is lost. Several times I've been using the tracking feature to track a moving vehicle while I was in it. I've lost connection each time (expected while inside a metal vehicle) and the Phantom started to fly to the home point.... miles away! I had to jump out quickly and switch back into P mode to save the Phantom.