Edward Tufte, a professor emeritus of Yale has previously written about the problems of Powerpoint http://www.edwardtufte.com/bboard/q-and-a-fetch-ms g?msg_id=0001yB&topic_id=1 , and gives the example of how the 1986 Challenger explosion could have been prevented if NASA didn't rely so heavily upon it for presentations. In summary it's about how Powerpoint is a poor tool for communication, As opposed to just text, or speech.