Pros
As a graduate student: - Resources are plentiful. IT, facilities, libraries and the rest have most of everything one could need. Shared instrumentation facilities are of high quality. - Size. The large size and variety of the work happening at MIT means that there are knowledgeable people in almost any relevant area that you can seek advice from. - Nerdy atmosphere and great variety in people. It is difficult to feel left out. - Nice campus and excellent recreational facilities
Cons
- Chief potential downside: Principal Investigators can be "hands-off" to the point that it is possible to get stuck in difficult / vague projects for extended periods of time. It is essential that you take initiative and exit or enter projects depending on your own judgement. - In some groups advisers can be ambitious in a way that translates into significant pressure on graduate students to put in lab-hours or achieve results. This depends from group to group.