Pros
Stability, work/life balance, great overall benefits, flexible work schedule, overall respectful environment. This is not a company for everyone - it's best for people at a certain stage in their career when they are looking for the aforementioned things.
Cons
It's a very matrixed organization, everything is done by consensus, people are not willing to make decisions, a lot of unnecessary things get escalated up the management chain for decision making, slow moving changes, too much defending of turf, superficial and unnecessary need by some to display their position in the hierarchy. On a different note, since the offices are located downtown Chicago, there really is no good place to live that would be close to work - it's a heck of a commute for lot of people. But they keep commuting because of all the positive things at Northern Trust.