Pros
Once, there was great, exciting work, a commitment to quality and standards, and the feeling that you mattered. If you had the luck to be on a good team with a supportive manager like I was, the sky was the limit to what you could imagine and achieve. You felt empowered to constantly take on more responsibility, learn new skills, promote your ideas, and be compensated and appreciated appropriately. Even today, the people working there are very smart, and some are interesting. Microsoft treats its employees quite well. The campus is beautiful, the food is good, some people still get private offices, and the charitable match, tuition reimbursement, fitness, free commute and parking, and other benefits are fantastic. Plus you get a lot of prestige, respect, discounts etc. by working for Microsoft.
Cons
Anymore, Microsoft cares only for its stockholders and stock price. They will do anything, including cutting as many employees and programs as possible, making their products worse, and mistreating their users, to reduce costs and improve the bottom line. If you are old or female, if you work in content, especially if you have been successful and long-term so your salary is high, you will or probably have been axed. And that's just the tip of the iceberg. They used to hire "Microsoft material" and train you as needed, but now they hire whoever can do the job du jour for the cheapest price, then they will kick them to the curb too. No one's job is safe except possibly the upper management layer whose sole concern is to keep their own jobs and fiefdoms. Expect to work with lots of minimum viable products, cancelled projects, reorgs, office moves, and a weird Microsoft jargon that is mostly TLAs. Endless meetings and PowerPoints yet a lack of communication, wasted and duplicated efforts that can go on for years. Also expect your family and friends to constantly complain or seek your help with their Microsoft products, and to realize that a lot of the outside world hates or scorns Microsoft and with good reason.