Pros
The engineering work can be very rewarding, cutting edge. The environment is quite advanced in terms of diversity, safety, professionalism (probably due to an excellent compliance training program). The IT department is top-notch. Reasonable communication from management to employees. Very good use of technology in productivity tools; there are user-friendly web-based systems for employee services & benefits, training, time recording, news feeds, intra-company communication, process document control, and performance management. There are advanced approaches to data management.
Cons
The pace at a defense contractor can be slow relative to a fully commercial enterprise. Telecommuting is not an option for most employees, but there is some shift flexibility for most people (1-2 hours). There are even some part-time positions, but perhaps not as much as in other industries.