Working with lots of smart people
Pros
There are many smart people you'll see and work with. You can learn a lot from them. There are many different groups inside Microsoft where you can change the direction of your career with an internal transfer. Great amenities: commons mall and the library. Good discounts at the company store. Health benefits got worse over time but still very good. Access to gym is a plus. They generally support work/life balance, that might change from product to product.
Cons
Internal transfers are not very easy or encouraged. Definitely doable though. Currently going through lay offs which caused some worry among employees. Reviews are stressful with the curve system. They have been trying to improve this but it is still true. You might end up in a group with a bad work-life balance, you have to do your research if you value that.
