Pros
Benefits are excellent, but there is a glass ceiling if you are in certain research positions. With this company, 403(b) matching is vest immediately, which is excellent compared to other companies that take several years to become 100% vested. Also, it's great that the company observed Federal holidays, so that you don't have to use your personal annual live. Another benefit is that if you have already been with the company, but then leave to find another job, it seems easy to come back to another position with the Henry M. Jackson Foundation. Also, they count your previous time with the company when it comes to benefits.
Cons
This is a contract position, so if the contract is not renewed, there is risk of losing your job or having another company come in to pick up the contract.