Leonardo's writings that are in the book are relevant to artists today but I would have appreciated more commentary explicitly linking his ideas with the modern paintings and drawings that were included in the book.
Interesting concept - tying principles from Leonardo's notebooks to images of modern art to show how well they work even across many centuries and many stylistic changes in creativity. For the most part it works pretty well, though some of the connections seem a little forced or arbitrary. A good insight into Leonardo's ideas, however, and also an interesting way of re-examining modern art and seeing it with new, 500-year-old, eyes. Would be particularly useful to those just starting out on the great adventure of appreciating art.