Pros
For many employees, there are options to work on a variety of contracts and projects, which keeps the work interesting and different. Employees help each other out, sharing ideas and knowledge. Expectations for quality work are high, and for many projects, you can see the positive outcomes of your work with the government agencies. Flexible working hours - it's nice to be able to work from home one or two days a week.
Cons
Balancing availability for project requests. Maintaining the company line of "100% utilization." Training and professional development are encouraged, but must be attended OUTSIDE of the 40+ hour work week. If you attend an all-day training session, be prepared to work an extra 8 hours to make up for the lost time in billable hours. There is no additional compensation for those extra working hours.