Pros
Incredibly smart people as peers. Terrific benefits...fully paid healthcare (no premiums and no deductibles). Flexible work arrangements and respect for people's schedules. Seattle area is a great place to live and raise a family. More than any other company I've worked at, you have real chance to move around / try new things as you progress. Financial resources are unparalleled...if you have a good idea and can convince management of your thinking....you can secure funding / headcount to implement. There is a strong respect for individual opinion at MS...people are encouraged to speak up if they have a point to make without regard for hierarachy.
Cons
Work life balance is very difficult to achieve / maintain. Company is invested in too many areas now...it's feels like we are Peanut butter attempting to invest and cover too many areas at the same time. There is not really strong fiscal discipline although this is starting to change with the recently announced layoffs. The company has become more bureaucratic and less nimble as it's continued to grow. It relies too much on the Windows and Office franchises and needs to re-vision to role of software (and especially it's delivery) before MS becomes irrelevant. there are too many internal meetings and not enough time spent with customers / real people...Redmond is pretty insular.