Vantaggi
I have been working at Microsoft Consulting Services for a year and a half. On the bright side, they are in a moment where the company is redefining its own identity, embracing a lot of open source frameworks and technologies, and moving a lot of effort to compete in cloud computing and data analysis. You have many resources to learn about cool stuff, farther away from the old idea of what Microsoft is about. They are trying to change, fast and hard, and they are taking it very seriously. There are many internal opportunities and you can pursue them freely.
Svantaggi
Life/work balance is bad. You are expected to outperform in ways that, if you really want to compete, your free time will be consumed by a lot of extra stuff, always, and the compensations, at least as I have seen so far, do not, well... compensate. Collaboration is a cynical joke at Microsoft, a real theater. People are out there with corporate machetes in their hands, it's everyone by themselves, and God is against us all. Of course, helping others is a bonus criterion, so in the surface people is generous, but it's too much insincere and in most cases, for show. Traps in every corner, projects surprisingly mismanaged. As already known everywhere, Microsoft's evaluation system is doomed to create internal competition, and ultimately goes against everyone's best interest, the company included.