Probably the best part at being in DevTeach was meeting and talking with a lot of people. That was also the biggest frustration. The moment that there were more than three of us, the discussion split into several interesting avenues, leaving me really wishing that I could take part in at least three conversations at once.
I can (usually) take part in two discussions at once, but it is confusing (both for me and participant in the discussions), and there is some prioritzation that is going on which decide who I am most interested in listening to right now. Part of the reason that I like email for communication over IM/Voice in many cases is that it allows me to handle concurrent discussions better.
That said, there is nothing better to communicate ideas than a face to face meeting where you can easily interact with the person(s) you are talking to. A lot of the discussions that we had at DevTeach would be simply impossible to take to a written form and keep the same tone (which is what made it interesting in the first place.)