Pros
Benefits: Microsoft pays for everything, and then some for you and your whole immediate family. not just awesome health insurance, but huge discounts on gym membership, lawyer fees, restaurants, and more Resume booster: As many issues as Microsoft may or may not have, it is tough to argue that it doesn't look pretty good on a resume Industy experience: There are some very cool things going on in a variety of industries that Microsoft is playing in. Getting involved in these projects can be exciting and even historic in many cases. Internal flexibility: If you don't like your job, boss, team, building location, or even industry, take a look around internally and dip your toes in the water somewhere else. It is pretty easy to maneuver the internal job market.
Cons
Slow to react to industry trends: Microsoft has been historically about 2-3 years behind where they should be from an innovation perspective. See next point for the reason why. Too many meetings and approvals needed to make decisions: I can't stress this enough. Be prepared to move VERY, VERY slowly to get almost anything accomplished. Too many overlapping functions: There's fat in many of the organizations that could be trimmed. Another reason why it takes so long to make decisions. Engineering dominates most business strategies and decisions: This is how Microsoft was built, and it still exists in the corporate culture today. Not a bad thing, unless you're on the business side and you want to try and do the job you were hired for.