Pros
FIS provides opportunities to innovate. It can be a great place for new developers as they will get to do hands-on new technologies. Some projects provide actual banking domain knowledge. Improving company so employees can expect good growth. Work life balance is very good as they don't have much burning projects.
Cons
HRs can sometimes be very mean. They need to learn some manners and professionalism. You can't expect a good experience while joining. They have huge deductions in CTC when compared to other organisations. This is a very cheap trick to hire employees at lower pay scale. Previously Sungard was a popular company which got acquired by FIS. Many sungard employees are still in FIS and they quote that sungard was way better than FIS in terms of employee satisfaction and increments. Many projects have local level politics where more focus is given to some core people when giving increments.