Pros
The contractor leadership is pretty good, if limited in authority to actually control anything. They recognize the value of people and work hard to improve job satisfaction. The pay and benefits are really pretty good -- competitive in the industry, if not much better. Most of my coworkers are bright and motivated, and the work is fundamentally interesting. Note that a lot depends on which part of SAIC you're working for. SAIC is really a conglomeration of smaller companies. The organization that I work for was one such company, and as such retains a lot of it's original identity. Work here is VERY stable, which is good if you like to do the same thing for a long time.
Kontras
SAIC is ready and willing to do whatever it takes to make the government customer happy, even if that means making poor long-term decisions. Senior SAIC leadership isn't interested in rewarding performance. I led a team of half-a-dozen developers to a successful finish that leadership said we probably couldn't attain. It was grueling, and we won, and our reward for a year of pain and suffering was a lunch at PF Chang's on the company's nickel. Ouch. Work here is VERY stable, which means that growth potential is terrible.