My wife is finishing her undergrad at Dartmouth's MCB for microbiology. She absolutely loves most of the people she's met. A lot of the grand students are really easy to get along with. From her experience, the O'Toole lab is basically the greatest thing in the world. Dartmouth/Hanover is OK, (coming from a non-Dartmouth person) loots of snooty money running around. Pretty good campus food, but very expensive. Hanover has good food, some of it cheap. No good multiplex movie theaters for a ways. If you are outdoorsy like we are, it's awesome. Hiking everywhere, and world-class sport climbing right there at Rumney. Skiing is omnipresent, and Boston/Montreal/NYC aren't too far away. Bus service leaves something to be desired but the schools own Dartmouth Coach is pretty good but doesn't run often. Hanover is isolated from any even medium sized cities for about an hour in all directions...much more in some directions.
I have a friend doing work with the molecular biology peeps and she definitely found some dud PIs. Let me know if you have anything specific you'd like to know.