I'm also probably committing to MIT, in the biological division--It seemed like there were labs that weren't so great but the majority of people I talked to were pretty happy in their labs (Buchwald, Jamison, Pentelute, Shoulders). I think it really is lab-dependent, and as long as you find a good group you should be ok.
I was not expecting to like it because of quality-of-life reasons, but I definitely was pleasantly surprised after the visit weekend.