Pros
Great work/life balance. It has an unusual culture for a large corporation in today's society - it isn't focused on being the biggest, but the best. It treats employees well and provides good benefits. It's a very financially responsible and stable company. I feel very secure in my job, even when many other large companies are having to lay people off. It's a place where you can have a career.
Cons
It can take a while to get things through the pipeline. However, that's also one of the reasons why they are so secure, because they really take the time to think through their decisions. Don't expect a fast-paced business environment. Promotions might not occur as fast here as they do at other places. But sometimes a great work environment and stability is worth a slower climb.