Pros
Secure job. As far as I can tell, submarines are going to be made for at least the next 50-75 years in their current form. Not much risk of losing ones job at this company unless you steal or commit an HR boo-boo. Decent pay. Good benefits.
Cons
In no specific order: Parking is horrendous. Unless you get to work earlier than 7am, expect to walk at least 1/4mile into the office. Big time red tape here. So many levels of management and military involvement that sometimes it takes a miracle to get anything done. Mediocre work force over all. The company has no negative consequences for poor performance, which makes people lazy. Not much of a diverse culture. Most people are white males, with about half being <30 and the other half >45 years old.