My employer rolled out teams globally earlier this year. Tens of thousands of employees. Historically we used Webex for Conf Calls, and some internal software for doc management, also used Shareponit, etc.
I was a bit apprehensive, as I didn't want to give up my Webex account I'd had for years. While it took some getting used to, I find the conf calling features, and chat features to work well.
A short list of Pros (at least with how our system is configured):
1. While IT has to set-up the initial Team, I as owner, can add user delete user, add channels, etc. without IT support. Rather than submit a ticket, and wait for overseas IT support to fill it, I can add a user to one of my Teams in about 10 seconds. By the time it took me to navigate the help desk menu system, I can be done.
2. It's great having the ability to add exterior users (Teams calls them Guests) to my teams. For us, that's generally clients, or subcontractors. And the ability to chat with those Guests is great. We couldn't do that with Skype (how it was configured). I can also give Guests access to certain "channels" in my team. I generally segregated my channels into "Public (which technically isn't public just public to the Team members), Internal (company employees) only, and PM Private (my private space).
3. I find the chat, audio chat, and video chat features to work well. The background blur feature is nice in a WFH world. I can be driving an F1 car one day, sailing the next. I haven't had any issues with audio or video quality. And the variety of backgrounds creates some team building conversations.
4. The integration with Outlook is nice. A simple click to add Teams info to a meeting invite. I also like when I'm doing notes (in OneNote in Teams), I can click a button and get all the meeting info imported into the note (name, time, date, meeting attendees, etc)
5. The automatic back-up features are nice. I already had one new to Teams person try to get fancy by syncing it directly to the Windows Explorer, so it kind of shows up as Network Drive (not the right term). Similar to Sharepoint. They sync'd a number of folders, and then just decided to delete the folders they didn't end up wanting, not realizing that it was deleting the files in Teams as well.
76 The history feature is nice, as it's difficult for employees to do the I'm working on it thing. I can tell who's been in it, when they were in a file, etc.
Cons:
1. People working in the same file at the same time is functional but seriously quirky. Ie, if you two or three people are in the same Excel file. While the feature is awesome for some applications, it can be quirky.
2. I find myself almost always using the "open in desktop application" button, for all Excel and Word files, unless I'm only popping in to view something. Any serious editing is easier in the full application.
3. Not Teams fault, but I have it on my laptop, Ipad, phone, etc. With the cause barrage of chat popups, it sounds like machine gun fire between all the devices all the time. I know I can fix that.
4. I haven't found a good way to do true Document Management, Revision Control, Transmittals, etc. yet within Teams. Sure you can do it all manually with separate folders, etc., but not in the same controlled way as our traditional (but ancient) document management software.
5 I find the presentation (display my screen) feature to be a little less user friendly then webex, but that may just be how many years I used it.