Pros
Driven and intelligent colleagues and fascinating science, amazing lecture series on campus, robust development opportunities for entrepreneurship and impact-driven science. An inspirational air of technological intrigue and ambition.
Cons
Cog in a machine, PIs level unreasonable demands against students and are more often than not poor managers/mentors. More profit-focused approach to IP and spinouts than MIT would like to convey. Experience will be one part what you make of it, and one part happenstance - if you have the bad luck of getting a tyrant or egoist as a PI, your life will be very difficult. Your work for 5-7 years will be for the glorification of your boss, and unless you bring in external funding, you'll primarily help them pursue their agenda - par for the course for grad school, but know the risks.