Pros
It's a professional environment with a very stable corporate structure (which is something I'm very grateful to have in these uncertain times). There is low turnover and a good deal of support for furthering one's education in order to grow within the company. At least, that's true in my area. Your mileage may vary.
Cons
Much depends on who you work for. I have been extremely fortunate to work for intelligent, hard-working and fairminded supervisors. But as with any company, there are definitely some higher-ups who I have heard some less-than-glowing things about. I feel very blessed to be in a department where my diligence and hard work is both noticed and rewarded. There are definitely people I would not want to work for here. 9 times out of 10, it becomes pretty clear in the 1st interview what kind of person you'd be working with so you usually know what you're getting into right off the bat. Don't assume anything; ask tons of questions--and network, network, network every chance you get. When things change around here? They change fast and with little or no warning. Be prepared and always have a Plan B.