Pros
Microsoft is a place where you can literally spend an entire career at, doing different things, growing and changing in accordance with what you want at any given time. Want to work on servers? Microsoft has it. Want to work on portable media players or console games? Microsoft has that too! Search, databases, communication, operating systems, distributed technologies, office productivity, hardware innovations, you name it - if it's software, someone at Microsoft is probably doing it! And if no one is doing it, you can start your own Startup at the Microsoft Greenhouse project. And that's only the technology side. You can change your career path - e.g. from a technical maverick to a marketing wizard - with Microsoft's full support and encouragement. Training is part of the culture. Microsoft offers relocation opportunities, which means that if you want to live in another country for a few years you can do that without leaving your workplace. There's even a program that will send you to China for 6 months if you're interested. When life changes for you and you want to slow down a bit, there are even part-time programs. And if you read until here, you probably noticed that I did not mention the Microsoft recruiting mantra of “come and build software that will change the world”. That may be true, but for me it’s all about the company and more importantly the people that work there. Most of the folks you’ll meet at Microsoft are nice, passionate, honest folks that are just a pleasure to work with. I have looked at jobs outside of Microsoft several times, and have not yet found anything that made me want to jump ship.
Cons
Much like how the moss in Seattle can easily take over an entire lawn, if you are not careful, Microsoft will take over your life. Work is really addictive, and people tend to work very long hours, work from home, work at night and over the weekend, and let work fill up most of their lives. It’s hardly ever the case that a manager would ask you to stay late and work on something – you’ll do it yourself, because you are passionate about the things you are building. This is a very hard habit to break and you need to be able to set strong, clear boundaries for yourself so that you do not sink it too deep.