Nadella's Microsoft is the new Microsoft. Before Nadella, Microsoft looked doomed to a slow demise behind the increasing irrelevance of Windows, with revenue from (local-only) Microsoft Office as the only future source of income.
Nadella has changed the course of that staid ship by changing the underlying culture, no small feat! Some specific actions: Microsoft Office on iPad and Android, going all in on cloud (Azure has 22% of the market, ahead of GCP's 7%, at the start of 2019), being friendly with Linux (Windows Subsystem for Linux - WSL, exFAT specs were released a few days ago), given up Windows Mobile (he “did not get why the world needed the third ecosystem in phones”).
https://www.inc.com/scott-mautz/microsoft-ceo-satya-nadella-...
https://qz.com/work/1539071/how-microsoft-ceo-satya-nadella-...