Read their privacy policy! https://us3-base.cd-n.net/client/html/pp.php

They collect EVERYTHING about you including things like your phone number, unique device ID, email, hardware model, which websites you visit, when you visit them, etc..

and they give it to third parties. I guess they should be lauded for being relatively transparent about this but how many people are actually reading the privacy policy?

I can't believe this is rated so highly...