Pros
SMS goes after and hires the best. They're primarily a Government (DoD and Federal) contracting firm so new opportunities are constantly presenting themselves. SMS will attempt to keep you on should a contract end or fall out from underneath you. This down time on "the Bench" is usually used for self improvement (Certs) or temp work. At Christmas time Bert throws a great party at a country club in McLean and life at the HQ is never dull. When you reach your 10 year mark with the company Bert will present you with a Rolex at the Christmas party. He doesn't believe in making folks wait 20 years for a watch.
Cons
If you're on "the bench" more than 2 weeks you had better prepare an exit plan. Anymore than 2 weeks you'll generally get the tap on the shoulder and given another 2 weeks to find another job. Management will do what it can to place you in a position but it doesn't always work. You live and die by by the contract.