I had no clue what the app did untill I visited the "about" page. Normally I don't have the patience.
The snippet explained me the entire app. Perhaps some of it belongs on the home page.
How does PaperKarma work?
The PaperKarma app enables you simply snap a picture of
your unwanted junk mail, press Send, and get
unsubscribed. That's it! Just snap your junk mail away.
(In about 24 hours you'll receive a notification that
you've been unsubscribed. You can always use the app to
check on the status of your unsubscribe requests.)
Those stats are great hooks, but I doubt your potential users would need convincing. You stop spam for yourself first and foremost, that it helps the environment is a nice add-on.