The traditional student presentation format - ten minutes of powerpoint, two minutes of questions - rarely works well. After three or four presentations, a good chunk of the audience zones out. Getting a good discussion going is hard - and there isn't time for an extended conversation anyways. Then there are the logistical challenges - loading presentations, allocating the unpopular time slots, dealing with late students and no-shows.
This term, my class did poster presentations instead - and we are never going back to powerpoint.