Pros
I've been there average amount of years and experience has been mostly positive. Bonus is good, benefits are about average for a financial company but above average overall. There is a good amount of mentoring and other programs available to employees. Flex work schedule is a great benefit as well.
Cons
As IT employee, current direction to outsource almost all IT functions to IBM India is questionable. There is probably a good strategic reason for it at executive management level but I just don't see company saving any money over it, and IBM India resources are not on par with average former State Street internal IT resources. If it takes 4 times a long for outsourced resource to do same job as US/UK local resource for 1/2 the cost - price to performance benefits are not being realized. Transition to IBM has created a condition where people with most experience and knowledge of the environment left or are leaving and IBM does not offer sufficient resources at the right level to pick up the workload. I cannot speak for other business areas, but for IT professionals my advise is to stay away from State Street at this time.