Vantaggi
The technical people here are exceptional. I've worked with leaders and pioneers in my field much earlier in my career than I could have hoped to. I also like the breadth of products that Microsoft builds, so the freedom to move from product to product as my career grows is valuable to me. My coworkers across the company are also a great resource - I've learned a lot about several Microsoft products in great depth thanks to help from my coworkers. The perks are also great - free health care, a great gym membership, lots of paid time off, and of course living in the pacific northwest.
Svantaggi
The work life balance is totally random. Some weeks/months I'll be able to do whatever I want, but some months I'll work 80+ hour weeks a few weeks in a row. Management attempts to fix this, but I've seen the pattern of poor planning saved by last minute heroics a few times now. We also have a tendency to get out of touch with reality. Not everyone in the real world has a quad core computer with 8GB of RAM and fast internet at home, but we get lulled into making that assumption because everyone we know here has all that stuff.