Pros
Worked for the Army as contractor through my school and it was an amazing learning experience. The people I worked with were extremely helpful and always stop what they are doing to help each other out. This was pretty refreshing given the negative image of government I heard before coming on board. You basically make your own schedule and do what you want...given you complete all assigned tasks for the day and you stay on top of your items. LOTS of training opportunities. My advice is to take all the training you can. Training equals pay raises in the Army.
Cons
Culture took some getting used to. Work with a bunch of "good ole boys" that all know each other from Vietnam days. As a 34 year old, it's pretty hard to impress these fellas. Upper management is lazy!!! Don't expect them to help you out much. Great program leaders but terrible team leaders. Upward mobility is a huge game!! If you don't know the rules, your career will be dead in the water.