As of today, Google’s app promotion ads are available on the Google Search and YouTube networks. The app promotion ads are an enhancement that sends users directly to the appropriate app store to download. You can choose an ad format optimized for app promotion that displays all the details related to your application.
Google’s app promotion ads are designed to get apps in front of the right audience. Ordinarily, it encourages advertisers to use app promotion ads in search for new installs.
App download conversions
If it's an Android app from the Play store, installs display as conversions in AdWords without any extra set-up.
The ability to integrate third-party app tracking analytics
Analytics information with AdWords and see installs counted as conversions by enabling auto-tagging.
Automated bidding using Target CPA
when creating the app campaign to find the optimal bid without waiting for conversion history to accumulate.