Pros
Good on CV. In the top 100 companies in the world because of turnover.
Cons
Joke of a business. No one ever knows what's going on. Lots of admin even for small stuff like 10-20k buys. Love to hire new graduates as they are cheap and get them slogging hours. No consideration for people who have a family life. Managers easily expect you to do 10 hours everyday. They get you to sign an long hours waiver form when you join so you can't complain later. In the UK they always go begging to the MOD for more money even though they ship saved money off to the US. You only succeed in the company if you work like a donkey for 4-5 years. Training only given to folks who will work like donkeys. Common sense approaches don't work as they love to make things complicated so they can get more money out of the MOD.