Pros
Smaller company size gives employees more familiarity with management and the atmosphere is generally pleasant. Employees have zero reservation in approaching executives and mid-level management are great. Employee turn-over is relatively minimal and many that do leave do so so for a permanent position with clients. They invest in employees without clearances and find work for them elsewhere while they wait. They're also eager to send employees to training that isn't necessary, but is beneficial. There are multiple members of the headquarters support staff that have worked their way up through the company. Mid-level management are very accommodating with paid time off requests.
Cons
Benefits have been changed to "make the company more competitive," which means that overall compensation for employees took a hit. Adjustments to the 401k plan now require employees to contribute an extra percent to maximize employer matching, which is now a percent less. Medical benefits went up ~25-85% depending on your situation, but this is down from originally proposed the ~65-150% increase that was met with a lot of backlash. Additional paid time off can be earned through years of service, which is great, but resetting the clock for all employees really screws-over employees that have already put in several years. The promise of performance-based raises and bonuses is always in the air, but no one can seem to remember an instance of it occurring. End of year bonuses and raises are the same across the board, regardless of performance. The company wasn't financially prepared for the government shutdown and increase in medical costs, so Christmas bonuses are set to arrive sometime in early 2019. A lot of the contracts are limited in scope and the smaller size of the company doesn't afford a lot of opportunity for professional growth for contractors beyond their current position. Contractors are left out in the cold if the company loses a contract, whereas larger companies are able to move them to different contracts.