Pros
There are a lot of very well connected people walking the halls in McLean, VA. It is a very interesting environement to work in, you have to be very comfortable dealing with the government red tape. Compensation was acceptable, but I did have to work hard and negotiate it back up to where I was with my pervious employer.
Cons
They said you can meet anyone from an Astronaut to a Prima Ballerina when I hired on and they were correct. But, they also enticed me with an overseas opportunity... unfortunately when I actually joined three of the key people within my group quit! (all at once). They had had enough, this was an extreme case and does not happen often. Given how slowly partners react to their internal organizational troubles it makes sense...