For the developers, Teams works... as good as Teams can. So not great, but it works most of the time (for me, anyway). For everyone else though, I hear nothing but issues. Constantly having to restart to make Teams work. And again, this is on Surface devices, so Microsoft is making the app, the OS, and the hardware!
Even aside from the performance, I just think Teams is laid out horribly and it stifles communication. The redundancy between chats, group chats, and Teams channels (which are like a message board?) is just bizarre and constantly causes confusion. It's so much worse than Slack (which we used to use, and I used at a previous job) where all communication channels are listed along the left side, and you didn't have to dig through menus and trees of categorization to get to certain places to talk to your coworkers. And since Teams channels are sectioned off behind another screen from your chats (where you'll probably be most of the time), the only way to be aware of when someone posts in one of the channels is to turn on notifications for it. Which is very annoying!
edit: oh also a recent update made it so when you paste a code snippet into the plaintext editor thing (whatever it's called, you activate it by typing 3 backticks), it strips all the whitespace from the left, meaning you lose all the code indentation. Just great