Pros
the comraderie and knowing that you're doing something to help protect the nation. at some locations and for specific jobs, the actual work is amazing, both in interest and overall impact. plus, you get the chance to move around and see places that you otherwise would not go. it's possible to be in a different part of the world every two years - for most other jobs, that is nearly impossible. there's also a good number of days off given through federal holidays, MAJCOM down days, and the leave that you accrue over the course of a year. i think it all adds up to aobut a month and a half of free time that you can take in a calendar year....
Cons
if you get stuck in the wron g place it is horrendous. you can move around a lot, but you run the risk of landing somewhere where you simply cannot adjust to the change in culture, you're limited in your personal life (i.e. cannot go to school as there are no good viable options, it's a small town so no sultural things to do like museums, shows, etc.) and in some cases even your professional life (i.e. for your job title there still a requirement, but the mission really doesn't utilize your specific skill set, so your professional talents are essentially wasted).