>the UX is so much better.
Meh:
Typing anything complicated is a weird mix of WYSIWYG and knock-off markdown, which causes confusion and frustration. Codeblocks and snippets in particular.
Random delays in getting rid of an indicator as there are weird, in-built checks and timers, forcing more clicks.
Bugs out messages, not able to send or receive (anecdotally only colleagues had this).
The weird split between Teams and Chats tab, which has practically no similarity to its competitors. The Teams tab feels clunky as a result compared to the Chats tab.
The Teams tab was randomly decided to scroll bottom-to-top, while the Chats tab is still top-to-bottom.
..and more. Making something better than Skype, Cisco and other stuff isn't that difficult given the underlying tech has drastically improved. Even so Teams routinely messes up trivial things over weird business decisions, and tries to shoehorn features that have been solved since the times of Teamspeak/Ventrilo/etc.
It's not terrible, but it's apparent Teams isn't that great and routinely emphasizes the wishes of management types over the wishes of end-users. No self-respecting developer would encourage one-click calls without the ability to turn it off. Voice channels solved that issue decades ago.