I've been pretty happy with it, but I'm also a programmer with interest in and knowledge of why it's important and how it's useful. I can see non-technically-inclined family and friends being very confused by it.

To bad theres no GPGTools for iOS. And the chances of Apple opening up the mail client for it is slim. Also, the licenses could be a problem?

Seconded. Unfortunately the webmail services don't have the same simple interface.