Pros
CGI Group (CGI) acquired American Management Systems, Inc. (AMS) in May 2004. For approximately 2 years, the United States division was known as CGI-AMS (as a way to continue the brand loyalty of AMS clients). Right before AMS was acquired (at the time, CGI tried to sell it to AMS employees as a "merger" - no one bought that), the morale at AMS was poor. For awhile after the acquisition, the morale among former AMS employees went down. This is pretty standard. Over the years, there has been some improvement in making the former AMS employees feel as if they belong to the company, but for the most part, people still think of themselves as "AMSers". This doesn't seem to get in the way of everyone working together to get the job done.
Cons
As with most firms, different people have different experiences. I wouldn't disuade anyone from applying to CGI.