Some of the more interesting points were: (1) an explanation of the pressure to conform, and why this pressure is surprisingly high even among those who consider themselves independent thinkers (2) the power of being first to speak in a group and the efficacy of a firm and confident tone (3) the two types of dissenters: contrarians and disclosers; and the importance of disclosing one's opinion and reasoning (4) discussion of "groupthink" and how group opinions form based on the group's members.
I appreciated Sunstein's frequent reference to psychological studies. That made this book much more credible and useful than one where an author merely formulates theories and writes about them.