Vantaggi
Microsoft has a great reputation. It definitely opens doors if you wish to engage outside the company. It also hires diverse people who are generally quite driven and interesting. There are also a plethora of products that one can get interested in, work on, play with, try out and just get involved with. The company is also growing older which means that there is more respect for diverse work styles.
Svantaggi
Microsoft suffers from many problems of large companies. The original culture has been watered down by bureaucracy, rules, fiefdoms, feuds, and politics. The stack-rank compensation system creates the need for employees to create their own visibility resulting in people favoring appearances over output. There are also limited opportunities for rapid promotion as the slow product cycles, ranking systems and politics get in the way. In the subsidiaries, you work at a severe disadvantage to Redmond in terms of resources, working conditions, career paths, and general opportunities. Your pay, however, may be better in a subsidiary (although benefits are not kept on par with Redmond).