Avantages
The PhD and MS programs at MIT's Operations Research Center have a very collaborative culture, with graduate students constantly sharing ideas, supporting each other, and teaming up on research projects. The faculty vary in their supervising styles, but students generally enjoy a good amount of autonomy. MIT provides excellent opportunities for entrepreneurship and business teaching, which is especially great for those interested in business academia or tech.
Inconvénients
There are plenty of general cons to doing a PhD (in any field), but I can't think of anything specific to our program. Perhaps it is fair to say that some of the faculty are so successful, and overstretched, that students may get less face-time and direct mentorship than they might receive at other institutions. And as with any university / department, not all faculty get along and sometimes faculty politics can taint the advice students receive (e.g., who you are encouraged to collaborate with, whose courses you are counseled to take or avoid, etc).