Pros
It is hard to find anyplace else that gives you the freedom to get the job done than at Microsoft. There is very little micromanagement. The groups that I have been in focus on execution and getting stuff done versus the process around how you got it done. By and large you have access to great resources and minds to accomplish big things.
Cons
Creeping in of Bureaucracy. With the arrival of the Walmart / GE execs they are bringing more scorecards and process (six sigma) which theaten the execution focus at Microsoft. This is good to some extent but there are instances where some managers go overboard and before long you are forgetting that you are trying to get a job done vs. complete a process and fill out a scorecard. There are also the development methodologies dujour -- but I suppose that exists everywhere. It is also hard to get things done if you don't know people. There is a resistance to change at Microsoft so if you introduce new ideas or way of doing something it can take much longer than you woudl like to move forward.