Pros
Professional and friendly co-workers. People are mostly expert in their fields and they are very reasonable. They have standard benefits such as 2 weeks vacation, 401k , dental - vision and health insurance. They conduct yearly reviews where they set your yearly raise and future goals. Senior managers and project manager are incredible good at their jobs and help/teach you as much as they can.
Cons
Even though they are open to new ideas and technologies, being a government contractor limits their resources them such as work laptops are old. When a new technology or opportunity arises they can't really invest like other well funded companies. Dress code for applies to everyone, which doesnt make sense if you are a developer who is sitting in the cubicle 8 hours a day and rarely see a client or attend interviews. There is not much a company culture where you can meet with other people in the company or build team spirit.