Pros
Ability to gain some experience, understand office culture, networking, company has deep pockets so if you land in the right department (anything corporate - not fund or service operations) there is chance for nice perks.
Cons
Sometimes the company is too big for its own good. If you want to do anything or change process, it takes forever and environment is highly bureaucratic. The industry is highly regulated, so preforming change management is sometimes implausible. Many people that work here are "sticks in the mud" no matter what department you work for, they are all over the place. People tend to ‘pass the buck’ here, blame others for problems or would rather claim ‘it’s not my problem’ than actually sitting down and solving anything. This place needs a serious culture change.