Pros
Microsoft has great products that are unbeatable and will stay around for a very long time to come. Its people are really interesting to get to know and not just nerdy. On a personal level, I found almost everyone enthusiastic and friendly with a "can do" attitude. And I am proud to call those I know well my friends.
Cons
There is an over-aggressive culture that permiates through the business. The HQ culture is arrogant and does not understand how the rest of the world works ie: outside the West Coast. The subsidiaries are pure money-making operations with little empowerment to make decisions. The "on line at all times" mentality means that people never have a break from the business, so despite lots of talk about "work / life balance" it is work work work.