Pros
Microsoft has a very extensive breadth of opportunity, across a variety of job functions and product lines. Transitioning between products is encouraged (as long as it is not taken to an excess). Most product lines have an amazing ability to make a broad and global impact on people's lives. In specific roles, your work can make a tremendous difference to the success of a product. To top it all off, there is a relatively fantastic benefits package, especially when you factor in healthcare costs.
Cons
As a large company, your ability to impact the stock price signficantly as an individual is non-existent and you must rely on less lucrative reward systems which are and highly competitive. Due to its size and approach, Microsoft does not invest in business opportunities that are small, even if the relative payback ratio could be high, resulting in a diminished entrepeneurial capability. The company has an adolescent management culture, without functioning and proven frameworks for growing its next set of leaders. The competitive review rating system ensures that folks that are great contributors but have reach the highest level of competence are forced out to competitors after a time.