Pros
Good teammates, depending on team. The salary is better than those of most startups. The stock is not just lottery tickets unlike most startups. Some great benefits, such as the ability to put additional $33K (instant Roth conversion) into your 401K after topping off your max annual contribution ($22.5K) and Microsoft's match ($10K). Decent LWB. Decent perks. Okay insurance.
Cons
From what I hear, not all organizations within MS are the same. I, however, have only seen one. In my org, we have a codebase that is truly unpleasant to work with. It is bad in every imaginable way, from size, to readability, to performance, to architecture. What makes this worse is the fact that engineers are expected to do the work of product and project managers as well as DevOps. That's in addition to our own work. Theoretically we have product people, but I've never seen them do anything useful except maybe some really high-level stuff. Everything that a PM does in any other company, your team is expected to do. You will see a lot of people who've been at MS for decades. They've not seen much else, or have seen it so long ago that they have no understanding of the current state of tech. And because they've been here for so long, they have a lot of weight. That's why that codebase is such a disaster and why it will remain a disaster despite constant efforts and initiatives to improve it. No architect is ever gonna say "I messed up, this is all bad, delete it" or "We decided to use tech X because it seemed cool, but we don't actually know how to use it, so we applied it in the same exact way as we know how to apply the old tech Y". And despite tech X actually being awesome, the team produced a monstrosity because all they know is tech Y and reading a couple of tutorials didn't help. To be fair, there are a lot of smart people here, who care about code quality, but the higher a person gets in rank, the more they care about looking important and covering their own behind. The company itself is gigantic and therefore a bureaucratic nightmare with proportional amounts of Kool-Aid being distributed. After the layoffs we are expected to "do more with less" (as if that wasn't already the case) and we won't get a cost-of-living pay increase this year because of "difficult economic situation and uncertainty". That was announced a few weeks after a record-breaking profits announcement. There is also an eternal corporate song in the air, about supporting the latest trend. At the moment it's diversity, inclusion, equity, social justice, etc. Obviously, the company doesn't actually care, none of them do, but it has to project an appearance or be eaten alive on Twitter. So just smile and wave and you'll be fine. Overall, it's just another large corporation. You can have an amazing experience, or you can have a terrible experience. It all depends purely on the org/team that you end up in/on.