This biography is wonderfully readable. Some tics that imply bad editorship remain, like quite frequent repetitions that ‘light hits the whole area of the retina’ but overall context is refreshed well. I think what helps is Isaacson’s willingness to remove the aura of professionalism from the biography, his personal beliefs, however they may stack up against Leonardo scholars, are stated and stated clearly and that makes his enthusiasm come across too.
I love the context that Isaacson adds for example many at the time used mirror script. It strips away the magic and brings Leonardo down from the heavens to us as a normal person, although I worry at how selectiveness that context is at times.
The reminders of how different life was like in 15th and 16th century Italy is delightful. There are bank transfers and anatomy classes, but also random invasions from France and an inability to apply paint durably onto walls.