Several privacy concerns. Players can connect through Facebook, create a username that is shared with others, and display a picture as their profile icon. Once you're logged in through Facebook there's no easy way to log out and remove your photo. They can post their performances for all the app's users to hear. They can also leave comments; some users will leave contact info in comments (Skype, for example). If enabled, the app will detect the user's location and broadcast it to other players as a dot on a world map. Users can opt out of this feature.