Vantaggi
As a private company, GA is free of trying to satisfy stockholders, which affords a lot of freedom that most defence contractors don't have and avoids the feast or famine of government budgets. Good job stability. A fair amount of flexibility. Salary and benefits are pretty good for GA employees outside of California.
Svantaggi
This is NOT a good place to learn how to develop good software -- engineering process is made up as they go along instead of leveraging industry practices and tools. Functional organization means that engineers are interchangeable cogs expected to put in a certain number of hours on a project according to some manpower plan, making it hard to develop a good team. There's no investment in training. As a defense contractor, hours must be logged as though you're an hourly worker, but overtime isn't paid. Opportunities for advancement in technical areas are poor, and there's very little recognition of high performers. There's a lot of self-imposed bureaucracy and parochial business practices. Progress is slow.