Pros
Depending on the department you have the opportunity to work on some great programs. And the museum itself is great. Just walking onto the floor can liven up your day. Also all the employees are great. Every one is really friendly from senior level management to the security/housekeeping staff. Great place to be. Newseum/Freedom Forum is also really great about letting you know you are appreciated. Also Newseum has pretty good benefits...they used to be GREAT with tuition/medical reimbursement, but those got that axe (along with sabbaticals). Maternity leave is 6 months (AWESOME benefit), partial employee match with 401(k).
Cons
Depending on the department, NO growth potential and low pay. I've been there for 5 years and STILL haven't cracked $40k.