Where do I even start…

• The verification process constantly breaks
• Sessions get randomly unverified
• Pictures aren't being send occasionally
• Their client is a UI/UX catastrophe
• Room Events are incompatible (esp. w/ Element X)
• The "experimental" voice rooms are total trash, settings are not working (e.g. auto-gain can't be disabled)
• The Calls via Jitsi somehow have a worse UX than Skype had in its worst days
• The verification via emojis uses different emoji styles, missing the point completely
• Due to the session mess "Can't decrypt message" will be your best friend
• Even if you got a verified session it sometimes fails to decrypt a message
• The federation is SLOW. As in "wait many many minutes" slow.
• The whole Spaces-with-detached-rooms concept is a mess
• There're no proper moderation tools
• There isn't even a god damn admin panel! For the longest time you had to MANUALLY CURL THE API. Even today you have to mess with third-party admin panels that usually don't have all options exposed
• Encryption is nice, but Matrix leaking tons of metadata isn't.
• They effectively stopped developing the Element client in favour of Element X, which isn't available in desktop. And also loves to break during verification.
• Third-party clients sometimes work better, but certainly don't expect anything but text chats with pictures there.

I really tried to like it, I even attempted to move a community over, attempted to self-host, all the jazz. It's a steaming mess for years now with no end in sight, and literally everyone who tried it eventually left disenchanted. Don't even bother trying it.