Pros
One of the reasons I enjoyed working for MasterCard was the camaraderie between my colleagues and the way the departments were able to interact with each other. I also felt comfortable with knowing that if I needed to talk to Management about something, that the door was always open. I liked that they had plenty of resources available to increase your knowledge base, and they encouraged self improvement as well as career development. Management was quite flexible with time off and I saw in most cases they were willing to work with you if you needed something, be it advice, assistance, whatever.
Cons
The only real downside about working at MasterCard was that there seemed to be frequent reorganizations. It makes for tense management, in my opinion. Some other downsides were the political aspect of working in certain departments, but you will find that in any office. As with any and everything else, it all starts with the people.