Pros
Get to work with some legitimately smart people. Working remotely is a possibility. Starting salary is ok for this type of position. Might be a good experience for certain graduate school fields.
Cons
No opportunity for career advancement for bachelors level employees. It is a total degree-tocracy. PhD and masters employees will spend no time attempting to mentor or develop bachelors workers. This is due to the fact that all time worked must be charged to a project or overhead account. Managers can be particularly parsimonious with this money. Pay raises are small, and non-existent in some cases. Employees are expected to be driven by love of research, not the possibility of any financial reward. Large amount of work is done over the phone and email with rare opportunities to interact with other employees in person. This created numerous communication and morale problems. Revenue is almost entirely from the federal government. Business is dependent on the fiscal whims of Congress. Bachelors employees are often assigned more menial and time intensive tasks because they are cheaper. Actual research opportunities can be varied.