Ventajas
As a government contractor you frequently get many government benefits such as Alternative Work Schedule, government or "bank" holidays, and and access to some government only locations/benefits. Being a government contractor makes for a relaxed work environment.
Desventajas
Emphasis on "safety" for IT workers is irrelevant at best, idiotic at worst. Managers are incompetent and unable to adequately manage their projects and employees. Many employees are overworked on overtime, while others lie fallow. Emphasis on bread and circuses rather than career improvement. Networking and knowledge sharing is non-existent. Training coordinator is horrible. Acts as if training is to be doled out stingily and with great suspicion. "Safety Minutes" for desk jockeys is a waste of time.