The most important feature in App Stats for us is the daily star rating. Right away we know if the day is better or worse than the overall average. It helped us understand what was happening with apps like HD Widgets so we could fine tune stuff and make everyone happier. As a result our overall rating badge for HD Widgets changed from 4 stars to 4.5 stars. Excellent!
App Stats also has summary lists that let us follow and compare apps together, so not only do we know how our apps are doing, we know how our competitor's apps are doing as well as popular apps, top apps, and new releases. For example, we watched Facebook Home debut with a really low rating (less than 2 star) and are watching them climb back up. Their daily ratings are still really low, but they're improving.
App Stats is also designed for deep diving into an apps history and performance. Each app has it's own dashboard w/ notifications of major events, ratings tables, rank tables, and history graph. The table cards provide recent data and tap-through to show 30-day history for their stats.
We've been using App Stats internally for about six months. As you may know, we're very diligent about customer support. App Stats was an extension of that: it allowed us to check-in on user ratings without going through a browser or developer console - we could open our phone and just look. Later on we added notification features so we'd know when new releases cleared - again so we could make sure there wasn't any problems for you guys.
For now this is a beta. We're waiting on the Google's Play Store update to finish, which should be soon. When we're ready App Stats will be a subscription service w/ details TBD. In the meantime we encourage developers to try app stats and send us feedback on what they like and what else they want in it.