With previous design (separate chat and teams) my main problem was switching of view to get to one or another and complete lack of visibility of updates in teams when in the Chat view. I don't use notifications, don't like to be distracted with popups for each message i receive. Like to be able to see where new content appeared and check it when i am ready for it. When i would receive a new chat message it would appear as a number on the Chat menu. It would be handy to also get such badge for Teams messages in channels i have made visible for myself. But there is none. So, when i am in the Chat menu i don't see when new messages appear in channels. This let to me constantly changing between Chat and Teams menu. I receive a chat message, i go there and talk with a person for some time. And then i have to click back to Teams to stay on top of other updates, back and forth the same way, very annoying.
So, i was excited to try this new approach. It kind of works and not. When everything is in the same view, no matter how compact i make everything i cannot keep everything on the screen at a glance. I do want to see more than 3 chats, but i also want to see all the channels, which is maybe 15 or so in just 1 team, but there is not enough space and i have to scroll to make sure there is no unread message somewhere at the bottom. Ok, i can use Unread filter then. It works, until you have to message someone back that you just had a chat with, but now it is hidden. Now i have to remove Unread filter, chat with them and then enable Unread again. This way it is even more switching than before. No, i don't want sections, i don't have such strictly related one to each other chats and channels. Most of them are unrelated to each other and i would like to have less manual management. Personally i would prefer to move unread content to the top of the list and move them back after you read it and clicked on another item. Then no scrolling is needed, doesn't even need Unread filter, no switching between views. And this works in other communication solutions.
Btw, with this new design, even if you are ok with just using chats and channels in the scrollable list, maybe with sections, etc. There is still one huge switching cause that drives me mad. Notifications menu. It is the same as it was with separate Chat and Teams. You get a badge that somebody replied or liked something, you click on notifications menu and then you don't see what is happening in channels and have to click back. So much unnecessary plane switching. In my world notifications would land in the same view above chats and channels, so you see everything in one view and don't have to go anywhere (can keep notifications menu separate if need to find something, but i doubt many care).
And finally, mobile version. Implementation is broken and not working often. Trying to use Unread filter and see new messages after a while involves constantly trying to refresh or reopen the app or switching between View all and refreshing the screen and STILL it often cannot show me new messages. Horrible.
So far this is not what i was hoping for and is not making my usage of Teams more efficient.