Pros
The most career choices, the most opportunities, the best benefits in the Seattle area. Some of the brightest people are employed there. You can learn a lot from others. The company is stable. There is a lot of support for Microsoft in the Seattle area. Microsoft is known around the world. Life/work balance is respected. If you want a change, you can always look elsewhere within the company. Free drinks, decent and affordable food available on campus. Main campus is beautiful. Relaxed, diverse, friendly, intelligent environment. Good commute benefits (free bus, etc). Telecommuting is supported. Software discounts, freebies. Somewhat "fun" morale events.
Cons
Decisions that get made are on the conservative side. Orange Badges are treated like second-class citizens. Commute is hideous.