I paste this into every feedback box I get:
Still so many bugs, not reliable, so slow at times, complex with multi-tenant, guest experience is very poor, switching identities and running multiple versions as web apps in browsers eats memory, too few things are pop out windows, team proliferation, poor experience to add someone to a chat thread, private channels implementation with SharePoint, especially when changing to public, renaming teams still not rolled out, sharing documents by meeting guests in the chat AFTER the meeting has ended, finding that chat again after the meeting has ended, still having to create a group to get a calendar