Ventajas
Pay is higher than other places, lots of different locations to work, depending on group you work in lots of interesting projects you wouldn't see elsewhere, good vision and dental plans, company has worked really hard at making inclusion better for people that aren't white and male (I thankfully work with a pretty diverse group), team and immediate management is great, corporate leadership quality is still undecided since Marylin Hewson left.
Desventajas
Your skillset is guaranteed to become out dated so it will be difficult for you to get a job outside of the defense contracting unless you have projects you work on your own time, health benefits are a joke (consider that bold and underlined at font size 30), they are trying to get rid of the "that's not how we do it here" attitude but older employees that refuse to retire make it difficult. You have to work with/for unknowledgeable government customers; which at best, is annoying