Pros
Large profitable company with lots of money in the bank. There are lots of opportunities to move around within different parts of the company, like Windows, Office, Zune, MSN, Enterprise, Public Sector, Consumer, Server and also geographically. The best environment for career and benefits is in Redmond, the simply have the critical mass to support a very comprehensive benefits package that includes subsidized drinks, health center, transportation, food, etc that subsidiaries like Canada can't. In Canada we are reviewing our benefits package finally. We have not changed it in 10 years! Hopefully it will be for the better, but I hear they will still not match RRSP contributions up to the max available. Too bad since there is no other retirment program from them and the stock has not moved in 8 years!
Cons
While Microsoft always tried to avoid being become large and bureacratic that's exactly what we've become. Our fear was always that we would become IBM after the DOJ settlement. Ballmer swore up and down that we would never fall into that trap, but the reality is with our size and the constant scrutiny be governments around the world we have become this generations IBM. Everything we do is scrutinzed by lawyers first, we all have to go through training to understand what we can't and can do for customers and partners, while our smaller nimbler competitors can react much more quickly than us.