Pluspunten
SAIC is a large, well established company which receives the bulk of its work from the defense industry. It's not going to disappear overnight like some badly managed hedge fund. It's not too hard to move around, and when your contract is up they won't just kick you out the door they'll actually try to find another contract that can use your skills (assuming you haven't royally screwed up on the first one). This is especially true if you have a security clearance.
Minpunten
Management varies *greatly* between the different business units! Not all of SAIC is doing well, so make sure your position is within a business unit with a profitable outlook...cannot emphasize this more. Don't expect an objective outlook at the job interview because they're trying to put their best foot forward. Also, you have to be proactive to get good work. You can't just sit back and expect to have the sweet stuff presented to you. If networking is key in "real" private industry, it's even more so in the defense industry which exhibits a lot of the 'old boy network' culture found in the military. Meet lots of people, ask what needs to be done (even if it's not entirely your area of expertise) and take action. Come performance review time, if you've only done what was expected you're gonna get a small raise...maybe 3%, and probably no bonus. The more people you meet & impress, the more leverage you have in demanding a larger raise...especially when you impress other contractors who just might be willing to hire you away from SAIC for a higher salary!