Most art books and magazines are about the product of art, with lots of four-color pictures to wow you. Leonardo is the opposite.
It’s pure process, pure tool — TECHNIQUE — of the most advanced, most refined, most modern of arts. (The news stays the same in this world; only science and technology change, and art chases them.) I view this publication with the same contemporary fascination as Science or New Scientist. They announce the present (i.e., future).
Not cheap, not for browsing. Lay out the bucks and make the magazine earn it back in your work or settle it all at your library.