Vantaggi
Easy to work work. PMs I have worked with are very responsive and actually give a darn about your personal growth. Benefits are excellent, although obviously you are going to pay for it. Also the company is pretty good about communicating about new positions they are hiring for.
Svantaggi
The main "con" I have is that there is not a lot of communication coming from HQ about what contracts are being worked on, knowledge-sharing between staff on different programs, etc. Also the benefits are a bit expensive, but on the other hand they at least have good packages available. Last item to me is the education/training benefit is not really sufficient; the level they will pay can easily be wiped out in one advanced MS class for example.