Pros
It's easy to get behind the Smithsonian's mission and a source of pride for employees. I met many very talented and intelligent people who were eager to contribute. From day one you'll have many experienced professionals with extensive contacts asking: "What do you want to do?" Professional growth is highly encouraged and everyone is remarkably helpful and full of advice. Demonstrate your dedication as an intern, temp or volunteer and you'll advance quickly (seriously, I met people at all levels who started at the bottom - including Directors). Salary and benefits are above average to great. There's lots of encouragement to attend Smithsonian events, or even check out new exhibits over lunch. Working in a castle doesn't hurt.
Cons
Demanding management diminishes retention rates. Directors don't receive enough admin support, and current admin policies are inefficient. Lots of paperwork, confusing and outdated data systems and organizational structures. Government culture weakens customer service, which is essential in development. Most employees punch out at 5 on the dot, even if the job isn't done (and hard work/overtime, while recognized, is rarely compensated). The lack of inter- and intra-department communication creates extra work. While people are eager to help you advance, no one seems to expect entry-level employees to actually stay in that office; don't expect to be "groomed." Upper management keeps its aims close to the vest, and even Directors feel like they're in the dark.