I made a module for Google Analytics Mobile App Tracking that I thought I would share. Some of the things you can track with this module: events, scenes, sessions, purchases, timings, social events and errors. It also has some basic offline support.
Its not using the native SDKs of iOS and Android but instead sends the payloads to Google via POST. From what I can tell there is not much downside to this, but then again I have never tried the native method.