His memoir "Hit Refresh" [1] was a reasonably interesting read, so
I hoped at least a bit of personality. But this reads more like an internal memo from CEO to the ranks vs personal notes (It can actually aim to public version of their internal memo.)
A good start would be Hit Refresh [1] written by Satya Nadella.
In this book he explain the issues he found in the company long before he was a CEO (basically, by the time he became the CEO, he knew what was not right).
[1] https://www.amazon.com/Hit-Refresh-Rediscover-Microsofts-Eve...