Highlights include Sliding Sync (instant login/launch/sync), Native OIDC (industry-standard authentication), Native Group VoIP (end-to-end encrypted large-scale voice & video conferencing) and Faster Joins (lazy-loading room state when your server joins a room).
@pezhore XMPP and IRC (to my knowledge, which very well may be outdated) are quite similar - you join a room from a client, you get a nickname, maybe a few lines of history, you chat, you close your client or lose connectivity, you don’t know anymore what’s happening there. You want to join from another client, that’s a separate session, with a different presence and name on the channel. Your clients don’t share history etc. [2/n]
@pezhore With Matrix, depending a bit on channel settings, your account joins the room and gets either all history or starting from the point of joining. And your account is in the channel. Regardless of what clients you use, and how many of them you use, and whether they’re online at the time or not, it’s your server keeping track of what’s going on in the channel, and keeping history of it, so you have one presence and same view regardless of type and count and connectivity of clients. [3/3]
That’s not true in the case of XMPP: upon reconnecting, any modern client will request from the server enough messages to recreate the missing history (of course it’s up to you/the client to put a limit to that if you want).
I think even IRC(v3) is taking that route.