Pros
Your work is important and valued since the U.S. Census Bureau is the source for many of the population and economic indicators in the U.S. As an IT person, I'm always working on various data collection instruments that each have unique requirements and will change as time passes. There isn't as much of a chance to get bored as there is always something coming down the pike. Also being across the street from the Green Line of the Metro, it is easy to get to the office. Some divisions have ample opportunities to travel for work, especially if you work in the Geography or Field divisions. Census does offer flexible work schedules and telework, which many of us take advantage of. Generally there are good opportunities available career wise, just be ready to change divisions on occasion.
Cons
The location of headquarters is not in the safest of areas, Suitland, MD, though nothing has happened to me. If your'e not a fan of eating in the cafeteria or bringing lunch from home, walkable options are limited to Subway, Popeyes, Chinese, and Pollo a la Brasa. A number of divisions have been going through reorganizations so there has been the growing pains of shuffling departments.