Matrix is a protocol for enabling real-time communication between different service providers.
Ranked in these QuestionsQuestion Ranking
Pro Built on an open standard
Matrix is an open standard, defining simple HTTP APIs so that devs can easily write their own clients, bots, bridges or servers. You're not locked into a specific set of implementations.
Pro Bridges other networks into a single decentralised network
Matrix has bridges to IRC (freenode, moznet, oftc, snoonet etc), Slack, Gitter, Rocket.Chat, XMPP, SMS, SIP and others. The point is to 'matrix' all the different networks out there into one single decentralised network.
Pro Does not require a centralized server to establish a connection between two users
Matrix is decentralized, there's no one central point that the information goes through and so no once central point of failure or control.
Pro Has an easy to use client called Riot
Riot.im is the easiest way to use Matrix, with great clients for Web, iOS and Android (and Fdroid).
Pro Supports different kinds of communication
Matrix is designed to support Instant Messaging, VoIP/WebRTC signalling (voice and video) and Internet of Things communication.
Pro Offers choice of clients
Pro Maintains full conversation history
Pro Has an app store for 3rd party integrations & bots
Riot.im includes an app store with integrations for Github, JIRA, Jenkins, Giphy etc - and anyone can add more via Matrix.
Pro Has an active community behind it
Pro Can be integrated with existing communication services
Matrix is designed to support Instant Messaging, VoIP/WebRTC signalling and Internet of Things communication and allows cross-communication between those services. Meaning one person could be using IRC and another Slack for IMs, or one person could be using Skype and another Google Hangouts for videoconferencing.
Pro End-to-end encryption
Con Can only "redact" a posted message but neither "delete" nor "edit" it.
The ability to edit a posted message is a powerful feature that has come to be expected since the rise of social media. Several other major chat platforms include this feature. Matrix.org's protocols enable you to "redact" a message (mark it as redacted whereas it is removed from view), but not truly delete or edit it. Deletion and editing are in the works, but in the meantime... CON.
Con Keys cannot be checked automatically
You cannot automatically check keys of your recepients. Only manually.