Pros
Able to work from home. If you have a IT it's easy to get hired by CGI. Good place for new grads to get that first 2 years of experience. Career wise all CGI is useful for is to keep holes off your resume. If you lack ambition CGI it's the place for you.
Cons
Pay is significantly below industry average. CGI has some of the worst benefits and the most expensive health insurance I've encountered. CGI is one of those shops that throws bodies at jobs regardless of the person's experience or career desires. Since CGI it's a consulting company there is very little opportunity to work with current technologies or to learn new skills. I worked for CGI for 5 years and during that time I was never given the opportunity to work on projects using current technologies (5 years of working on .NET forms doesn't make for good job experience). There is no opportunity for career growth, when you quit you'll be doing the same thing you did when they hired you. You'll be treated like a cog in the machine by CGI and you'll quickly find out they will discard you at any down turn in business or when by they lose the contract you are working on through incompetent management.