What does Microsoft Teams do well? Built on the foundation of Skype for Business, Microsoft Teams is a direct answer to the popularity of Skype, which combines team communication, audio and video conferencing, screen sharing and collaboration on files. It does a pretty okay job at that long list of tasks, and for users of Office 365 it's a no-brainer to adopt Teams instead of spinning up a separate instance of Slack at an added cost to the business.
What does Microsoft Teams not do well? Teams takes the minimalist and flat aesthetic of the rest of the modern Office 365 suite into the team collaboration space. It's a personal preference, perhaps, but this design doesn't really work for me in the team collaboration world. It's utilitarian in a way that screams "I'm doing work" instead of encouraging a little bit of fun and a more lively environment for conversation, the way that Slack does. It does its job well, but lacks flair.
What do you wish you had known about Microsoft Teams before using? Teams makes a few other apps that your company may have been using redundant, like Slack and Zoom, or Discord and Skype. Putting together the team collaboration tools all in one place makes sense, so in a way Teams is the culmination of an idea that started at Microsoft in the 90s with things like SharePoint. I feel dirty even saying the word SharePoint, but that's the legacy that Teams is built on. Something to think about when getting started in Teams, but probably not the thing that will make you decide to use Teams or not. If you're not an IT decision maker, you probably don't have a choice in the matter anyway.
Have you used a competitor to Microsoft Teams? If so, how does it compare? I've used Slack, Skype, Zoom and many other platforms that offer team chat, audio and video conference, screen sharing and document collaboration. None of them are as full-featured as Teams, which has the advantage of plugging into the wider Office 365 suite in a way that a combination of Slack and G Suite can't, and probably never will. That said, Teams is a bit more of a walled garden, so if you live that Office 365 lifestyle, Teams will be great, but if you have tools outside of Microsoft, your mileage may vary.