Nicoll manages to give a good view of the personality of Leonardo da Vinci, by describing what is known about da Vinci's childhood and then proceeding to describe his career as a *painter* in chronological order. Although in describing character Nicoll occasionally falls in depth into Freudian mumbojumbo, he has to be complemented that he does recognize that it is only fantastical speculation. The style of Nicoll is enjoyable and easy to read.
If you want to a good description of da Vinci the painter and his career, then this is the book for you. Nicoll goes in detail to the creation of many paintings of da Vinci, both those well known to general public and those less well known.
However, if you want a biography of da Vinci the multitalented man, then this book is definitely not for you. More space is given for description of a single art project that never came to be than is given to all the inventions and scientific contributions of da Vinci. As an example, Nicoll mentions that in the field of anatomy da Vinci's original contribution was greatest, and then proceeds to give six pages and two illustrations on the topic. And, unfortunately, most of these six pages is on the usefulness of the study of anatomy to a painter. More room is given to speculations about the possible identity of a female model in a painting lost hundreds of years ago than is given to the actual contribution of da Vinci to the field of anatomy. There is no description of the state of anatomical knowledge at the time and no description of how Leonardo added to this knowledge.
If you did not know anything about da Vinci before reading this book, you would finish with the impression that he was a mere painter and sculptor who never really did anything else - except dreamt of flying because of some Freudian type of childhood problem. Admittedly, paintings are perhaps the most lasting contribution of da Vinci, but they are not the reason why his figure appears in comics and novels, e.g. in Pratchett's Discworld books in disguise of Leonard da Quirm.
If the painting part was cut by 50 % and replaced by more detailed description of his other activities, this could be a very good book.