Being a coach on Chess.com, I've given about 10 lessons via the Analysis Board, a very nice teaching tool which helps convey lessons and materials in a great way that doesn't require
sharing screens and/or computers in Skype / Team Viewer etc. It did take some time to get used to it, both for me and for my students, but then the usage became smooth and pleasant.
Drawbacks: I haven't found anything seriously bad yet, I think there were some bugs a couple of months or more ago, but now they are seems to be fixed, and my trainings go smooth. Or maybe it was simply a misuse by me or my students.
One of my American students says: "It took some time to get use to it, and then it became a great tool, especially combined with voip such as Skype etc. All you need for a good lesson".