Pros
The IT department has mature processes that have been thoroughly vetted and work well. They form the basis of a model that can be taken anywhere. Learn and move on. For the most part, they have great people who are extremely knowledgeable and willing to help.
Cons
It is one of the most highly political places I've worked. Cross the wrong person, even inadvertently, and life becomes miserable until you just give up and leave. There are basically two camps: Old Guard and Young Turks. Old Guard still winning, but they are thinning out. There are some outright vindictive VPs and Directors. Not the norm, but tolerated nonetheless. More and more, they are turning to the field to fill corporate management positions. Be prepared to pay some heavy dues to get to management.