Privacy

Unencrypted by default (among other bad defaults), leaks metadata like it was built to do so, makes it surprisingly difficult to tell what's encrypted and what's not, filled to the brim with bugs and exploits, bad feature interop between most clients (most of which have known vulnerabilities or abandoned dependencies), defacto-standard "just use synapse/element if you want things to work properly" (and still doesn't), bad user communication about well everything but mainly teaching new users what all the things mean (session, verification, 1:1 vs jitsi, when you're using what,...), ton of federation issues and bugs, ...

And despite all that it somehow has a massive csam seeding problem, which really just makes me think the whole thing is a telegram-like fed psyop but one level higher on the tech competency ladder.

... Multi-device session chaining is a neat feature and surprisingly user-friendly (tho no one maintains their session list or verification; half pebkac admittedly), so that's something nice I can say about it... But almost nothing else.

Seriously, Signal is basically a joint three-letter-agency sigint project and I still think it's safer and easier to use than matrix for the vast vast vast majority of people