Pros
Some divisions have unique, cutting-edge research. If you can find those, you're all set. That said, however, SAIC is great at farming bodies out to customers without regard for employee morale or preference. If they can put you in a dark hole for their desired rate, they'll do it. Turnover while I was there was incredibly high; they lost 60% of their new hires within the first two years and struggled to mitigate that issue.
Cons
Too much bureaucracy to wade through to make a difference. It seems like there is a manager for every two engineers. They focus too heavily on hiring ex-military, and it shows too strongly in their management style. They need to balance their senior management hires to help sway the organization back to a more balanced level. That is unlikely to happen, unfortunately. The company has just gotten too big to be inspiring.