I generally like Isaacson's, biographies ... I've read enough of them; Einstein, Franklin, Jobs, "The Innovators" (my least favorite). The linked is a good summary of the book.
I was struck by the "pseudo Christian morality" the elites "adhered to" in Leonardo's time. Pretty much all the rich and powerful men, including Popes and the rest of the Catholic hierarchy, had a mistress or two, and probably a similar number of illegitimate children. Much like Egypt, Greece, Rome, and England at the peak of its power, wealth and power were the coin of the realm - plebeian mores were for the plebes!
I suppose we ought take the fact that immorality is more egalitarian in our time? -- "everybody's" doing it. Based on the priests abuse of children, the Catholic church seems to be proof that "power corrupts" has not been repealed by "progress".
It was also striking how devoted Isaacson is to the idea that if you are intelligent, you can't possibly have Christian faith. On page 512 we see: "In his will, Leonardo commended his soul to our Lord Almighty God, and to the glorious Virgin Mary" ... Which Isaacson immediate dismisses as a "literary flourish"', even though the page also says that Leonardo specified that his funeral should include three high masses and three low masses".
Leonardo is clearly a mythic hero figure for Isaacson, and it is just too much to consider that with all his "heresy" -- he would be in good company with Luther on that! Any disagreement with Catholic dogma was heresy.
On 487, "This is the heart of Leonardo's philosophy: the replication of the patterns of nature, from the cosmic to the human".
One of themes of the book is that Leonardo had an insatiable and eclectic curiosity, and was just completely fascinated with eddies in water, curls in human hair, birds, anatomy, and documenting his observations in notebooks (but not publishing).
The book seems like an excellent introduction to art appreciation, and least for me ... who is sadly lacking in that area. It made me want to see the Mona Lisa more. More than I needed to know about sfumato and squaring the circle.