The Daily Princetonian had an article about this today and last Friday:
Putting Humpty Dumpty back together again - The Daily Princetonian The incredible vanishing approval rating - The Daily Princetonian
seems like there are some significant issues here. As for the "sheen wearing off", couldn't that also be interepreted as students just being better informed about the place? Juniors and seniors have been there for longer, and should have more substantial views (much fewer of them have no opinion than freshmen). The trends seem fairly dramatic.