Pros
If you're in a BU with good contracts, it's pretty stable. Plus, if you do well, go the extra mile and get recognized for it, there are plenty of opportunities throughout SAIC to keep your employment relatively steady. If you have a family to take care of and would like to make sure they get provided for during economic downturns, this is definitely a company to consider. Lots of people here have been at SAIC for 5,10, 15+ years and there are many reasons why. There's enough of a mix of cutting-edge technology to keep things interesting but without the risk of your company closing its doors for good when things get tough (been there, done that, got the tee shirt). For the patriotic American, SAIC also offers the opportunity to be a part of something bigger than yourself while "serving" your country without the sometimes limited government salary.
Cons
You will come across people that are not the best at what they do but there are plenty of others that are very good at what they do to keep it interesting. The staff is older and many are ex-military but that's expected out of a government contractor. If you're looking for an internet-bubble type of hair-on-fire pace, then look elsewhere.