I love doing these with my students. Once they are comfortable with the format (and classroom discipline), I sit outside the circle so they are truly talking to each other, not to me.
Because they must use textual evidence, this forces students to find information from the novel to back up their opinions.
In my classroom, a seminar is a 30-point grade. Students understand that they are expected to make three meaningful contributions in order to get full credit.
In response to an earlier rating, I revised this product to include explicit teacher directions for those unfamiliar with the Socratic Seminar structure as well as a makeup assignment for students who are absent.