Pros
Decent benefits in terms of everything from 401K matching to health care to education reimbursement. Depending on where you work, you generally will never need to worry about working overtime. Flex scheduling is very nice for getting errands done. Managers are generally pretty understanding people and make a conscious effort to not practice favoritism and to be respectful to everyone. They practice the attitude of "I'll get out of your way and let you get your work done" which is pretty nice. They will not micromanage you. Once you get a job here, it will be a pretty stable job. Work is rewarding in the sense that you know you are doing work that protects the nation.
Cons
Besides the typical downfalls of a larger company (insane amount of bureaucracy, politics, etc.) ... Since secret work is being done, there are extremely tight rules for almost everything you do there. While these things are necessary, it means that things move even slower than a typical larger company. Boeing, or at least this particular place, is having a very difficult time stepping into the new century in a lot of ways.