We learned a lot from our NPS form implementation in the iOS app and applied those findings to the Android platform. Like on iOS, we released the form on both phones and tablets. Promoters are encouraged to submit their rating to the app store on the confirmation screen.
We implemented a labs feature on our Android platform as a proving ground for items that require a lot of user testing or iteration before a wide release (audio updates, for example) as well as other features that serve small but passionate users.
When users switch on a labs feature, and then use it for the first time, they are prompted to send feedback about it. Users can always send feedback from the Labs page.
After every fourth session, users can choose to leave a rating and feedback or tap on Skip to return to GoToMeeting.