Pros
FIS is a wonderful place to grow and learn, and generally the teams you will work with are full of great people. There is plenty of opportunity to grow your own knowledge, gain experience outside of your core competencies, and it is not difficult to become a core team member/star player who gets good recognition by management at all levels if you are willing to apply yourself and use common sense.
Cons
Different groups have wildly different strategies, work environments and policies; you may have to move around the company to find a good fit. Acquisitions have been allowed to run as stand-alone groups too often, and they tend to keep the "us/them" mentality, creating a lot of politics and mixed agendas. They run lean on staff, and that can leave you in the hot seat for lots of long days/weeks depending on your job role. Management also tends to continue to leverage star players, working them to death, rather than dealing with the team members who are not pulling their weight and replacing them with employees who do.