To Me! iT needs more tweaks. His principles ARE great, and his techniques helps you understand, what pencils are meant, to do what. And he trains you how to be in *Control, an discipline Your world.
iF you explain the ideal belief of art. Or the existence of creativity, that makes planes, tools, houses, etc,
iT brings strength, value & philosophy.
--But to me, he could've done a WAY better job..... So,... a beginning artiest wouldn't/might not understand his lessons. You have to have SOME TYPE of inspiration/moral for art. Before trying out his teachings. (Atleast... i had to lol )