Pros
Being surrounded by great people, great process, and inundated with "Best Practice" causes you to learn in a year what it would take 3-5 years to learn anywhere else. You also have the ability to have a huge impact in your customers/ your company and most manager's I've had are very hands-off which also helps you to help grow. Working in an environment where there is constant change is stressful at first but helps you to learn to deal with change; a skill that is useful for the rest of your life.
Cons
Work/Life balance can be a problem, depending upon the role. The compensation and benefits package in non-US subsidiaries is sub-par compared to the US Sub (especially the health care package). The tools and business practices are not standardized between the US and non-US subs either. The MS Performance system claims to be based upon metrics and to eliminate favortism, but when all is said and done, your manager will argue for you in the "Calibration meetings" if he/she likes you, and lesser-so if they don't. Favortism and the "good 'ole boys" club is alive and well; both in performance reviews and hiring. The focus on performance metrics has caused FAR too many people to lose focus on what is best for customers and the company; everyone is busy trying to check off items for their performance reviews and inflate their metrics instead of providing cusotmers with better products and services. The combination of the focus on metrics vs. what is right and the fact that many teams are geographically distributed and never physically see each other causes the team dynamic to break down and causes a lot of back stabbing. In a nutshell there's too much of a focus on individual performance vs. team performance.