Pros
They hire the best. My coworkers were top-notch and I miss working with them. Though they are a government contractor, you are hired as an employee and not to a specific contract. That means if the contract goes away you aren't necessarily out of a job and they do their best to keep their people. Some senior and middle management were great.
Cons
The lack of breadth and depth of the contracts they had combined with government cuts meant that even though they tried to keep people employed, they were facing the hard task of letting people go. They were working to rectify this and I believe they'll get it balanced. I didn't see much in the way of opportunities for career advancement. Some senior and middle management weren't so great.