I got a chance to play with the new Messenger a little while ago, and it’s remarkable for… basically not being remarkable. It looks exactly like the existing Messenger, but everything is protected using Signal protocol. Supports web and mobile, and just kind of works invisibly.
This is a really big deal. Although the full rollout will take a little while, this isn’t opt-in encryption. It’ll be full end-to-end encryption for billions of users, complete with encrypted backup and disappearing messages built in.