Teams is a nightmare. Instead of just creating the simple chat that everyone was just asking for, they went full PhD and created a mix between a chat and a forum.
A Teams "channel" has counter intuitive behavior, the messages you send are more like forum threads, users can reply to them, and when that happens it reorders the whole messages to put that one at the bottom. It makes it impossible to "catch up" on a channel since people will happily reply to any messages so the ordering is completely random.
There is also a completely counter intuitive distinction between "groups chats" and "channels".
Teams is also the only chat service I know where there is an actual limit on the number of non-public channels you can have. After 30 channels have been created, you're doomed.
Want to remove an existing channel to make room for a new one? Nope, you cannot remove a channel, only "archive" them. Archived channels are removed after 30 days and there is no way to force their removal early. So basically if you reach 30 channels you have to wait minimum 30 days to create a new one.
Did I mention the UI is slow as hell, and half the screen space is used by unnecessary large padding between messages? I am rarely able to have more than 3/4 messages displayed on a 23" screen.
The only positive point of Teams is integration with outlook 365 and meetings. It works really well, quality is good, reliable, nice UI, présentation mode, screen share, etc