Pros
Job security, nearly impossible to get laid off, Hours for most people are consistent, generally a good benefits package. You are able to jump around laterally within the company very easily. Once you get to T3 and above the salary becomes decent for prime standards. Easy, almost non-existent interviews.
Cons
Not moving fast enough in the current defense market. Lots of red-tape. Turnover at specific sites are insanely high. Promotions take forever and the increase in salary is minimal. They don't care about retention. They will let you walk and give your replacement a sign-on bonus and a higher salary. There are a lot of slackers and old timers riding it out till retirement. Only about a 1/3 of this site is actually productive. Yes-men get into management and ignore technical experts. Agile hiring is a huge issue where people are just thrown onto random teams. Easy, almost non-existent interviews allow people without relevant backgrounds to join teams. Every site operates completely differently.