Want to find out how popular the app you’re downloading is? Google Play Store is rolling out to more users the ability to see how popular an app is. Right below the Install/Uninstall and Open buttons you’ll see what the rank of a particular app is. Perhaps this might sway your decision whether you wanted to download a specific app or not. Google was seen testing this feature out last fall but it looks like it’s being released to more users now.
Source: Android Police