Pros
Obviously it is a place with a huge wealth of expertise and talented, ambitious individuals.
Cons
As a postdoc, there actually aren't that many opportunities to take advantage of being at such a prestigious institution, and you are almost entirely isolated on the island of your research group. If you're having a bad time with your PI, there's more or less nothing you can do about it so your boss essentially holds your career in their hands. While this may be the case in almost all academic institutions, MIT has zero support structure for postdocs, not even an exit interview. I personally found the research culture to be very competitive to the point of being quite toxic, and confidence often seemed to come before competence, though this is only my experience of a single research group. This competitive culture seemed to be the same at the Professor level, as my advisor seemed far more interested in furthering his career than making genuine scientific advances.