Pluspunten
You can work on complex, complicated technical issues with other bright people. You can find someone in almost any field at the company that could legitimately be looked at as a world expert; I had the opportunity to manage projects in some cutting edge areas. The stock compensation plan used to be the best reason to work there -- that model is long gone. I came in in early 2000's; Sarbanes Oxley, then the IPO put an end to options as a way of incentivising performance, and there's nothing that came in to replace it.
Minpunten
The company is incredibly stove-piped. That was changing somewhat as I was leaving but it wil be a long road. It can possibly be attributed to the way the company founder set it up -- he wanted divisions to be contantly competing with each other so they would stay lean and hungry; also probably because he had control issues and didn't want any organization to get too big. What the result was is that you were constantly looking over your shoulder within the company to guard your 'sand box' against other divisions. I would say the biggest drawbacks to working at SAIC is that there is no career track for senior people; the compensation is so-so (forget about bonuses -- really); they don't want to hear your ideas about business opportunities. I was constantly struck by how the place must run on testosterone -- every meeting was an opportunity for one divison manager or another to spread his tail feathers like a peacock. Woe-be to the poor guy or gal that gets stuck as a proposal manager -- you get no support, get micro-managed by idiots who don't know anything about your business, and don't get a dime in reward after you've won.