An irritating book. Two amiable chaps egging each other on to put the world to rights, in this case the art world, without having to face conflicting opinions. At one point Hockney regrests the lack of people challenging his ideas so why not introduce a devil's advocate into this cosy dialogue. But in that case the book would not be so easy to make. All that was needed was a lot of hot air, a tape recorder, an audio typist and a big name. As for the photographic illustrations, you can see Hockney sleeping, getting out of his car, sitting in his car, standing by a dusty road, all these shots being the size of a large stamp and designed to fill the margins without copyright problems as they are all by Paul Joyce.
All this having been said, there are some insights, if you can be bothered to sift through the verbage. When you find them it's often difficult to know exactly what is meant because that is what conversation is like, vague and ephemeral. There's nothing new about Cubism here, that you can't read elsewhere in the comments of Georges Braque, Richardson's biography of Picasso and elsewhere. Not that Hockney is claiming to be original on this topic.
The book is more about photography than art so the title is deceptive. There are better illustrations than the ones mentioned above, I just find mindless padding irritating. If you buy the book, look at the photographic collage of the Grand Canyon, which reduces it to something mediocre. The only reason we can interpret it as the magnificent canyon we know is because we've already seen the kind of ordinary photos which Hockney seems to criticise. If Hockney's collage was your first view of the canyon you would wonder what all the fuss was about. Any artist taking on The Grand Canyon as a subject needs to watch his step and show some humility. How can you improve on a straightforward panorama? Hockney is perhaps guilty of hubris in this example.
Some of the other collages (all photographic?) are interesting, especially the groups of people and Hockney is an interesting artist. I think he's allowed himself to be exploited here in the production of a book which was easy to make and sell. Unlike his fascinating book about the use of optics by the grand masters where he writes saying precisely what he means, this rambling verbage will do his reputation no good in the long run.
I'm criticising the book rather than Hockney. All that was needed in the case of The Grand Canyon was some decent editing or some other critical voice which as I say this book lacks -- a breath of fresh air. No doubt Hockney has a problem with flatterers. This book can't be the only example of lesser people taking a ride on his fame.