interface is vey poor
App will not open to recent chats. It is not customizable in that way. It will not let you delete a channel. When you click "Chats", it won't show your Team chats, only these private ones. The Activity screen doesn't show you recent team chats. The app is called "Teams" for goodness sake. But the hardest thing to get to is the most basic team chat. WhatsApp, Messenger, GroupMe, and basically all text apps have this simplicity. You're Microsoft! You should do much much better with this.
Sean Ellis commented
The items in the user interface are not persistent. If you navigate to an item in one team, temporarily switch to another team to check something, and then back again, your initial position is lost.
Having persistent UI objects would certainly help to cut down the amount of tedious navigation required.
There should also be options to arrange the items within a team how you like, to make proper use of screen real estate, and to choose which items appear in the navigation bar, so you can get to the things you use most often, quickly.
There's really no excuse for not having decent customization options.
Also, forgot to mention that if in the Activity field, you click on the "Team Activity" in the mobile app instead of the "Feed" that it defaults to, it does not show your recent team chats. Thus, to resume a chat, the user needs to click the "Teams" icon on the bottom row, make sure they click on the right channel under their team, and then can resume their group text. It is unbelievable how much more complicated this is than the other basic texting apps. This seems like basic blocking and tacking programming. Searchability/organization is a weakness in most text apps, and I can see Teams has this. But in the complexity of that programming, you forgot the most basic reason that users like texting. It's simple/quick/easy. You need to go back to the drawing board and fix this.