Pros
The vast majority of the people you work with at TASC are wonderful people to work with. Most are not corporate minded and have a real sense of community and caring about each other. There is real potential to move up, if you are really willing to work for it. You are afforded a fair amount of liberty and time off, in addition to paid time off to volunteer for various charities.
Cons
Sometimes the corporate mentality takes over across the business and there is a sense of losing individuality in order to conform. It can be hard to excel beyond lower-middle management.