Pros
I was fortunate to get hired on to a project with a great team for a great project. There were lots of nice little perks like free snacks in addition to the company-wide free drinks, social events with food an beer, and occasionally meals were provided. Free parking is also a plus, even if it can be tough to find a spot on Microsoft Campus. The job itself was a great experience for me and I was allowed to be self driven. After learning the ropes I generally worked on my own, but if I needed help or didn't have the solution to a problem everyone on the team was more than happy to help. Overall it was a very positive environment. I especially enjoyed being able to work directly with people in the production and design teams, which made it easier when trying to understanding intended functionality of the product.
Cons
I was a contractor, which meant that I had far less job security and a rather sad excuse for benefits. No vacation pay, no sick pay, and the health benefits were a joke. I may have had a better impression of the overall experience if I hadn't been quite unceremoniously booted out the door with no two weeks of notice. Normally Microsoft has a general policy for contractors to work a certain amount of time before needing to take a 6 month hiatus before being allowed to return to the company. The contractors on this project however became assimilated into a greater part of the studio through some unclear and confusing policy which, we were told, meant an indefinite employment for "at least 3 years" and plenty of job opportunities to advance their career and even become FTE with Microsoft. Instead this turned out to be a bunch of bloated nonsense and after realizing that their budget was overblown, several people were quickly let go with no prior warnings.