You have to trust the servers with your metadata, and that the servers have their inter-server communication locked down, but at least you can choose/operate servers.

Some clients are a bit flaky with their e2e encryption defaults or from a UI perspective it is easy to send an unencrypted message (in a new chat for example) before noticing that was how it was set.

There are a few XEPs the server needs which enable things like OMEMO, efficient mobile data/battery use, offline and multiple device deliverability, file transfers, etc. Audio/video calling has various requirements as I think xmpp only facilitates the setup of the call.

Munin feels a little old and crusty, but just works. Over 20 years old now.

XMPP lacks good clients and suffers from fragmentation of protocol standards implementation

• For Android: Conversations is excellent, also on F-Droid if you don’t want to use the Google store.
• For iOS/MacOS: Siskin or iOS/MacOS: Monal.
• For Linux/Windows: Gajim or Linux: Dino.

“Protocol fragmentation” is not a valid complaint about XMPP – it’s like complaining that ActivityPub is fragmented; but that’s not a problem: you use the services (Mastodon, Lemmy, Kbin, etc) built with it which suit your needs, mostly interacting with that sector of the federation (eg, Lemmy+Kbin), but get a little interoperability with other sectors as a bonus (eg, Lemmy+Mastodon).