I've seen Mazur speak on this and he says a fair number of his students don't like it. Some of their reasons for disliking it apply more to most other institutions than to Harvard. If they've always been taught that learning mathematics consists of memorizing algorithms to apply to assigned problems, they may regard a more intelligent approach as grounds for complaint, especially if the reason they're there is to get an "A+" in the course so that they can forget about it and get admitted to medical school (admission to which requires calculus or the like, not because students need to know that subject, but because they need to have demonstrated that the can succeed in courses that are challenging).
So there's some danger of being punished for doing the right thing. That doesn't mean you shouldn't do it, but it might affect the way in which you do it.
