Vantaggi
You will be working with some of the smartest people if you are in the right group here. You will have an opportunity to learn so much about software engineering. Good facilities and perks.
Svantaggi
Too big a company and too many re-orgs. It hampers an individual contributor's growth. You will be learning Microsoft technologies a lot. These doesn't help if you look for opportunities outside Microsoft. You will basically be a person who knows only about Microsoft technologies and nothing about open source technology stack. A Microsoft engineer might not be that highly regarded in other big companies simply because of the technologies learnt while in Microsoft. Another issue is that you will be as good as your lead projects you in front of everyone else. So if your lead doesn't like you, you are screwed. This lead might not be the one who interviewed you and hired you because of re-org. So basically it is something like you interviewed for team A, but when you join, because of re-orgs you end up working for team B and totally different person who you did not meet during the interview time. Another thing is SDET career is not good at all. Anyone who joins as SDET is just wasting career here.