It's one of the better ones, and basic functionality is braindead, but I've definitely found some pain points.

• My work requires us to use company branded video chat backgrounds 🤮. Whatever way my co-worker deployed them, they aren't available through the mobile app.
• There's a feature to create unified groups (Teams groups) with membership lists hidden from non-members. It is only available through PowerShell.
• Got users that want to use their group like a distribution list? They all have to personally choose to subscribe to incoming email. You can set the group to auto-subscribe new members, but subscribing existing members requires some basic PowerShell fuckery.
• Sharepoint backend for file sharing. Less said about that shit the better.
• If a user's display name updates, how it syncs to different places that display their name in Teams and how long that takes is inconsistent as all hell.
• Better hope you never get a ticket from your legal team to pull chat history. Pain in the ass to do, horrid fucking output format.
• No way I've found to disable the damn upsell "Get Premium" button. Granted I haven't checked in a while.