Vantaggi
If you want to work for a behemoth organization and just be a face in the crowd then go for it. Before the financial crisis struck job security was fairly good, especially in IT where I worked so that could have been another reason lot of people, particularly in Vancouver, Canada remained stuck in their positions.
Svantaggi
From an IT perspective, it's a career killer. The technology leadership team is incompetent and only acts as yes-men telling the CIO what he wants to listen. The Household team (includes the CIO) is in charge and they're trotting out the same dog and pony show before business year after year. IT is touted as a force for change but status quo reigns supreme and there's no clear understanding of what business benefits IT changes can bring. Bottomline, If you're looking for a dynamic, fast-paced, forward-looking career it IT, this ain't the place to work.