Pros
Microsoft is a great company. Free drinks and cheap food at a great cafeteria. Unlimited resources, pretty much any kind of project you want to work on and a lot of mobility within the company. Opportunities all over the world. The new management really gets what needs to happen and it feels like the company is going in the right direction. There are some great people at Microsoft.
Cons
Organization tends to be unstable. You never know when you will end up on a new team with a new manager. Managers have unlimited power and virtually no accountability. They can make you a star or run you out of the company with virtually no challenge to their reasoning or facts. Great if your manager likes you. Terrible if not. Sadly not all managers are good.