Pros
The flexibility. My group is very understanding of taking time off to attend to personal matters and you can pretty much take time off whenever you like. Also, the company is very stable, so you don't have to worry about getting laid off. It's not an intense, high-pressure environment like you might encounter in the commercial world.
Cons
A lot of the flexibility comes from the fact that there is very little oversight. Everyone is off doing their own thing, working on their own little rice bowl, that oftentimes projects aren't big enough for small teams to work on, so some people are underutilized. For those junior staff that are utilized, it's pretty mundane and menial stuff. There is very little travel and "consulting" in the true sense of the word. I perceive the company more as "government seat-fillers" than management and strategy consultants. There is also a high focus on engineers, at least in the group I work in. I also think the company and its systems (HR, payroll, time charging, etc.) aren't well-developed, especially for a company that does so much IT work. Also, the compensation structure is very average. Your salary is on parr with everyone else, there are no bonuses, educational compensation is average, etc - nothing outstanding. Although I rated the company fairly high on the website's criteria, I'm not very enthused by this company and the work they do.