Pros
The pay is pretty good, people are friendly, no one expects you to stay later than you're scheduled, you get a lunch break. Coworkers are actually friends who hang out together on the weekends. The company is stable, even in rough economic times (perhaps especially in tough economic times, because people want to buy options to mitigate their risks). Someone here told me he didn't know anyone at the OCC who had ever gotten fired (and he knows everyone there). Job security is a plus, but don't expect rapid promotion or exciting work. Overall a decent place to work...for a year or so, until you get bored.
Cons
The work is slow, dry, and boring. The pace is fairly slow, which could be a good or bad thing. Many people have been at this organization for many years; I like the earlier review about this being a throwback to the 1950s. It very much is, perhaps because it's connected so closely to the government.