Pros
Brand value, resources, flexibility, ability to work from home. Plenty of smart people and perhaps a good place to learn how big companies approach problems and operate on a global scale. Great for technical people who prefer extremely well-defined roles where every process and procedure is already laid out.
Cons
Aging, stodgy, painfully slow promotion schedule, endless career ladder, and almost everyone's a lifer. This makes the environment incredibly myopic, political, and people are expected to stay well within their tightly defined roles and position on the totem pole. Workloads and expectations are high, and it's the kind of place where it's ok (and expected) for managers to regularly ream their hardworking staff the slightest typo, shortcoming, oversight, etc. As a result, people often fear their managers, who fear their managers, and so on.