Pros
CGI has great name recognition that makes you valuable elsewhere that provides great exit opportunities. One of the few things CGI invests in is training, which is a plus for those who need to develope critical skills right out of college.
Cons
At least in the DC area, CGI has become a burn and churn shop. There are only two ways to get raises, either threaten to quit or bring in an offer letter. CGI is notorious for 2% raise budgets and terrible bonuses. The pay and benefits are lower than competitors in the area that are jumping at the throat to hire their talent. New employees only get 10 days of vacation until they hit their 3-year mark, while competitors are giving 15-20 out the gate. Healthcare is also some of the worst I have seen.