Pros
Scope - MS has the biggest scope of opportunity for a talented software engineer, tired of working in networking, try security, or games, or windows, or office, or robotics, or research. There aren't many serious industry players that can offer that. Location - The pacific northwest is a great place to work Attitude - When applied correctly (and they sometimes are!) the company's values make it a great place to work. I'm not really talking about the free soda or health care, more the open environment that can allow smart people to really work together and produce. Scale - maybe this is just scope in a different light, but the company is big enough and diverse enough that I can see other teams doing very varied work
Cons
Talks down to its staff - amazing, MS has (or thinks that it has) an effective recruitment and interview process, which is meant to bring in smart employees, and in my experience does, then having recruited all these "smart" employees the company in any and all official communication with them talks down to them like they are idiots. Grrr.