Vantaggi
Personal development. I've been through the Engineering Apprenticeship (which is excellent) and since completed a BEng in EEE and a MSc in Systems Engineering, all paid for by the company. The projects are huge and there is plenty of opportunity to better yourself if you look for it! The people are generally great; helpful, and friendly. Working hours and time off are generally very flexible and where they are not, you get a big bump in pay.
Svantaggi
Working within security restrictions and export control can be very frustrating. Many of the projects began decades ago and the technology and processes can be outdated. Working environments, IT, can be very outdated. There is a process for everything. Things do not move quickly.