Pros
A multitude of diverse technical opportunities. Diverse workforce. Not going out of business any time soon. No civilian layoffs as long as I've known. COLA increases try to keep your salary aligned with inflation, when the President/Congress allow it.
Kontras
All that job security attracts employees who are perfectly okay with doing little or nothing. Supervisors are powerless to motivate them. At most, your performance might get you an additional 1% on your salary per year. If you're a high performer, you will be expected to perform everyone's work around you while they sit back and browse their stocks and investments, talk to their spouses on the phone all day or just fall asleep at their desks. This is not an exaggeration. The process for disciplining an employee for poor performance is so lengthy and full of holes that nobody bothers.