Context: I was at Microsoft during the first and only round of layoffs in company history (2009). My job was not impacted at all by the layoffs so I speaking from my memory of what was happening around me. In fact, I was working on an incubation project that was one of the few ideas that was green-lighted with a pretty sizable team that year.

My perspective:
From a company perspective, eliminating 5000 people in 2009 was a great idea. It was (and is) a huge company so it probably could have been more. However, the layoffs in 2009 were seriously botched. Many organizational best practices were violated.

Microsoft made an announcement saying that there would be ~5000 layoffs and that they would be completed over the following 18 months. This timeframe is too long! Layoff best practices say: cut deep and cut fast. Get rid of the people that have to be let go, treat them as well as you can on the way out, and then show some serious TLC to the employees you want to retain and rebuild your culture and trust with the people who stick around. Don't let the entire company live in fear for 18 months!

As much as the stack rank was a thing at Microsoft in those days, even if you were the lowest ranked employees for 2 years, Microsoft was hard-pressed to actually fire anybody. Even during this time of layoffs, Microsoft decided to divest in many businesses/products and chose not to eliminate people based on performance.

For example, they shipped one last version of MS Money and then the whole team was RIF-ed. Everybody on that team would get ~2 months to interview and find other jobs in the company otherwise they got a generous severance package and were no longer employed. Combine this with the fact that many Microsoft teams had recently restricted their headcount, it was relatively more difficult than it ever had been to find a job within the company.

The divesting strategy was interesting and it probably would have been a good way to do massive position elimination except that not all final versions of products were aligned to ship in the same timeframe. So anybody working on small-ish or lame-ish products had a fear for many many months that after shipping their current product, they would be out of a job. IIRC, this strategy of divesting took about ~12 months instead of the 18 months they originally announced before they provided comfort to the employees that the layoffs had completed.

This was also during the economic downturn of 2008 so there was extra angst from people who lost their job because they had just lost a lot of their net worth from a seriously depressed market. Morale suffered. Lots of good people defected to Amazon, Facebook, Google.

This time around, I hope Microsoft does a better job of keeping the timeframe for cutting to a reasonable period of time like 1-2 months. Unfortunately, even if you make it through the layoffs and feel secure that you have SOME JOB, you'll probably not really know WHAT SPECIFICALLY you're working on until all of the re-orgs play out. This is colloquially known as re-org hell.

Best of luck to the people impacted. It's a relatively better market this time around. If any of you make it to San Francisco, I'm happy to grab coffee or give you pointers on some cool companies looking for great people.