Pros
There is potential to do useful and challenging work at SAIC. Your particular experience will depend on your particular boss and contract. Top management wants to do the right thing by improving conditions for employees. They initiated this with a couple employee surveys in the last year or two, with results sent to local managers to improve the working environment. I suspect that in some cases, the local managers used the results to improve the environment for the workers. In my own experience, it seemed like the local manager(s) read the results, then white-washed the deficiencies and used the positives to justify their own performance.
Cons
Tend to manage contract paperwork. The actual work is contracted out to subcontractors. If work is in short supply, some managers will check with other local divisions to get coverage. Others may not do anything outside their own group, which was my experience. There are huge opportunities at SAIC, but it your are not in Virginia, those may be far away from home. At times, there is competition between divisions that prevents open communication to win contracts. This competition can lead to discouragement to communicate to empoyees of another division. It is a large company with large company issues and characteristics.