Pros
Offers good benefits and somewhat ok salary, but very interesting work. Most of the people are highly skilled, whatever their role, and hours were pretty flexible.
Cons
Two items for this: as with so many large firms, the higher up the food chain a manager is, the more clueless and often, the more arrogant. Fairly common throughout the industry. Maybe not so common and worse: within departments (say, accounting or proposals, contracts, can be any department, etc ) it can be like be like high school cliques, competing for resources and back stabbing occurs behind people's backs within departments quite frequently. Every man or woman for him- or herself. Hyper-competitive and cut-throat. This is something I and a number of others I worked with there have experienced. If you are new to the place, be very careful, figure out who your real friends are, if you can find any. Become friends with people in other departments for support and information about those in your own department. Be careful about doing great things too fast and too quickly, as jealous coworkers may work to undermine you.