Pros
In my experience, it's rare that you can work at a company where so many people are passionate about the mission. AOPA feels like that rare company and the passion is general aviation. Although not every employee is a pilot, the employees buy-in to the mission of protecting pilots' right to fly. The benefits AOPA offers are excellent--besides the usual medical, dental, etc., the company has aircraft that pilot employees can fly at no cost and, for those employees who are not pilots, the company will cover the cost of flight training. The dress code is casual, there are a lot of fun employee events like ice cream socials and Halloween parties, there's an on-site cafeteria that the company subsidizes, and employees are recognized for their achievements. My colleagues are wonderful to work with and I look forward to coming into work every day.
Cons
Because it's a smaller company, the opportunities to move to different areas within the organization may be somewhat more limited than at much larger companies.