Chatting on Line
I think if you can find the right reason to use it, it is a great tool. You do have to teach the students to write in as few characters as possible, which is tricky. Otherwise the kids are engaged in a safe environment to collaborate in. I highly recommend using this as a back channel for your classroom. It is very easy to set up. You can create an account and keep the channel open for as long or as little as you want. As a teacher you also have rights to delete what should not be there or to print all of the content.
How I Use It
I have used Todays Meet as a back channel in my classroom. The students were able to ask questions to me on the channel and I would either bring them up in class or another student would answer it on the channel. It is a safe environment where the students have to be concise in what they write, but do not have to be afraid to respond. The students can be anonymous or use their names depending on how you set it up. I have used it as an exit ticket and as a way to brainstorm on a topic. The students really loved working on Todays Meet.