Comment by anotheryou

Closed source, not end-to-end encrypted by default, end-to-end only device to device (so I can't swap seamlessly from a desktop to a mobile session). Not even the protocoll is open, so I am bound to their clients.

Sadly it was the only nice alternative when the snowden stuff was published. That means those of my peers who made it away from skype/fb/whatsapp are now on telegram.