Pros
Very mature company. Leadership is generally pretty solid. Great benefits though will be declining in 2013. Many, many different opportunities in Puget Sound. Much fewer opportunities elsewhere.
Cons
I work in the Silicon Valley office. The opportunities here are far fewer and at higher levels very difficult and frustrating. Almost every group in the Silicon Valley is a sub-group of a Puget Sound based group. At higher levels, way too much time is spent trying to communicate and politic with co-workers based in WA. This skill becomes more valuable than technical skill and is crucial for success in the Silicon Valley office. There is no such skill requirement for those based in WA, though the skill is rewarded. The company struggles hard to break out of the mold that was used for its early success. There are far too few people doing and far too many people talking about what to do. The current development model of PM + Dev + Test + (operations) incurs way too much friction. Too many people are serving in far too narrow roles for maximum efficiency. Several groups have made efforts to make this better, but the moment that something (anything) goes wrong with a progressive approach, these efforts are usually scrapped. Worst of all, Microsoft is failing in its efforts to be competitive for top-talent. The best new hires don't choose Microsoft and the stronger the employee, the more likely that they are just using Microsoft as a stepping stone to something far more lucrative. Microsoft's compensation system is not structured to reward the highest achievers sufficiently. As a result, they move on and leave the "B-players" to fight for the 225% of target bonus (10-30%) that is available to the best of the best.