Pros
Pretty relaxed environment, the work is pretty easy and expectations are low - if you like that kind of thing. It's a booming time for the defence sector, so there seems to be growth opportunities in the near future. The pay can be low, depending on your qualifications, but is very high considering what is asked of you.
Cons
Like everything government, everything takes 5 times longer than it should. Ridiculously ineffective administrative services. Tons of bureaucracy for the most mundane things (I've been waiting 5 months for a $10 parking refund). Despite the potential to do really interesting work, it rarely works out that way and most of people's time/effort seems to be spent on useless paperwork or reports no one will read.