Pros
Microsoft is pervasive in the industry across most segments. This affords a lot of great opportunities to work on a diverse range of technologies. You can work for a couple of years platform or tools and then shift to Azure or cloud computing -- few companies have this simultaneous breadth and depth. Changing positions in the company is relatively easy. At the company there are a number of opportunities to be involved in deloping products that you don't directly work on. Most groups are flexible in terms of the hours/schedule that you work. Most groups at Micosoft have a good work life balance (i.e. the days of death marches are largely over). The benefits are excellent.
Cons
The high level company strategy in areas where Microsoft isn't being sucessful is in constant churn. There is little reason to believe that Microsoft will start being succesful in areas where it is currently challenged. Innovation at the company can be challenging as there are a number of vocal critics to new approaches. Many of these critics have spent their entire careers working at Microsoft which limits their perspective.