Pros
At SMS they treat their employees like a family which is important in this type of industry where contractors sometimes rarely go to the home office. The company is still privately owned and the CEO still comes in every day. As with other small business when you do well your work is rewarded and every one knows eventually (this can be a con if you do not do so well). They work with some great well known federal agencies which, look great on your resume even when SMS is not recognized. Over all a great place to work with good people and an attentive senior management.
Cons
The cyclical nature of the type of work that SMS does can be a bit unnerving. They live and die by the contracts they hold. If SMS or the prime contractor holder that SMS often is under is kicked off the contract it can leave many employees in the hunt for a new position. Fortunately SMS has been good at weathering these storms.