Open Source End-To-End Encryption

On December 28, 2014, Der Spiegel published slides from an internal NSA presentation dating to June 2012 in which the NSA deemed Signals encrypted voice calling component (RedPhone) on its own as a "major threat" to its mission, and when used in conjunction with other privacy tools such as Cspace, Tor, Tails, and TrueCrypt was ranked as "catastrophic," leading to a "near-total loss/lack of insight to target communications, presence..."
-(via Wikipedia)

So, that being said, my experience with it so far has been that its consistently clearer, more efficient (less delay/lag in conversations), and more reliable than even Skype when calling on crappy wi-fi in Nowhere, Africa to developed countries. The only sacrifice is a very slight tinge in quality (barely noticeable "tinny-ness") and a dropped call once in awhile; both of which I find to be very, very minor annoyances considering my previous comments combined with the level of encryption applied. Well done, Open Whisper Systems.

theYellingGoat about Signal - Private Messenger, v2.2