Pros
Throughout my years with TSP I have always felt that I was well supported by my leadership as well as my coworkers. My management was always approachable and listened to my opinions and HR was always very responsive if I ever ran into issues or had questions. Even though a large majority of us worked in various sites outside of the home office they would try to schedule things to get us together outside of work such as company sponsored trips to see the Rough Riders or even things such as Whirlyball and social mixers. They provide a wealth of training opportunities and chances for employee engagement and really try to work with employees to help you grow in your career path. One of the biggest things is that TSP taught me to put value in myself, helped me to recognize the value of my contributions and knowledge, and has helped me make a lasting change in myself so that I can be more assertive about my own worth.
Cons
The only thing I could say is a downside would be be the same for any company in their position, the requirements for the contracts are at the whim of the customer.