Pros
No clocking hours: As long as I get what I need done, everyone is happy. If I need to leave at 3 for an appointment, I just let someone know. Abstraction from bureaucracy: I don't have to deal with higher levels of management. I talk to my lead and my PM, who know what I'm working on, and that's about it. Physical work environment: I started off with a two person office. Within a few months, I had my own. Comfortable chairs, nice computer equipment. Various benefits: Free public transit. Discounts at many restaurants and an IMAX theater downtown. Stable: Microsoft won't be going out of business any time soon.
Cons
Location: I don't really like traveling to the east side much. If I didn't work there, I'd never cross Lake Washington. Depending on when I drive there can be lots of traffic. Career opportunity: Promotions are rather slow and methodical. No fast tracking or anything like one would get at a smaller company