I have a couple of qualms about this,

Why should I as a user, believe that you the picture is actually removed from your server? The only true way of knowing it is if everything is open sourced. Or if you can get some kind of a license from some reviewing body (which i dont think exists) How is this different from snapchat? I can draw something on snapchat and send to my friend or some of the other chat apps which support this already?