Vantaggi
Microsoft varies immensely from division to division. The core divisions (like Windows, Office, etc) each hire thousands of engineers. You will spend all your time working on some tiny aspect of one big, great product. If you are cool with that, and cool with the idea that ten years from now you'll be doing very similar work for just a little more money than what you now make, Microsoft can be great for you. It is a comfortable big company with good pay. You'll have decent work-life balance most of the time (again that can vary from group to group).
Svantaggi
As an SDE at Microsoft, above average smarts are not really going to take you anywhere. You might end up in a group doing something cool and cutting edge, but your career trajectory and compensation are going to be the same as folks in some mediocre group elsewhere in the company. That can kill motivation over time. Microsoft has become too big and unlike the 90s it is no longer the most preferred tech employer. They no longer get the "best and the brightest". They hire way more SDETs and PMs than they need.