Pros
Good work-life balance - you don't work a lot. Good benefits. Good location. Free parking. Quiet neighbourhood. Generally friendly people. Large support community due to number of employees concentrated in one location. Lots of amenities and facilities such as common rooms, athletic facilities, playgrounds, parks, gardens, company store, visitor center, etc.
Cons
The company has no focus or direction. The employees are in an Orwellian state of denial. There is no honest discussion about pros/cons of any product. There is no direct honest discussion on decisions. Everything is awesome. Everything has already won. Bing is a winner. Windows Phone killed the iPhone in 2010. Windows 8 has killed the iPad by just being announced. Any other opinion, and you shall be branded a traitor.