Pros
Notes about the part of the company I work for only. Great and varied work. As an engineer you can plan a career that involves always doing something new - fascinating and hi-tech areas. The happiest people I know at BAE mainly want variety and work life balance. If your interest is in a varied career BAE is a great place to be. Great work life balance. In times of personal crisis the company is there for you and very understanding. Tends to be mature and well planned leading to relatively low stress (but this can be frustrating for those that want a real challenge).
Kontras
Can be clunky and bureaucratic. Bureaucracy not always linked to efficient or effective process. Which can be frustrating Company so large that pockets of bad practice (or people not being given above opportunities) is allowed to continue for too long. Fortunes tied to getting on a big programme - if you are a career climber. Affected by long term defence cycles. Leans towards groupthink. Difficult to sell good or needed ideas that don't meet organisations deeply set paradigms. Upwards management - meaning your job is to satisfy your boss and so on, not the other way around - this isn't really a con necessarily, but some people don't like it, especially if they are on the bottom rung.