Pros
Great group of people with which to work. If you believe in the mission, the work is fun. Lots of opportunity for working across the organization -- from communications to development -- and on outside projects (State Board of Education meetings, press conferences, etc.) Highly recommend for interns and jobseekers.
Cons
Unfortunately, due to the size of the organization, there is little room for advancement. There can also be office drama for the same reason. Internships may be paid or unpaid.