I finally got around to viewing the 12 episodes on youtube this past weekend and I must say that I was not that impressed with the discussion overall. Guess I expected more.
I noticed that Hitchens seemed to dominate the discussions and interrupted the others frequently. Dawkins was more of a moderator and did not add that much to the discussions overall. Dennett seemed slow to think and respond and missed the point a couple of times. Overall I think Sam was the most focused, coherent and made the most meaningful statements.
I also liked his book the best out of the four, although they are all good reads of course.