very interesting with a lot of references and comparisons to western theatre (which I admittedly didn't understand). clearly the author has a deep expertise in western theatre from the Greeks onwards and this allows for a very deep analysis of Japanese theatre, with explanations of what's going on on stage that seem accessible and straightforward.
it should be kept in mind that this was written in the 60s so Japan's position relative to the USA was rising although it hadn't reached its later heights; and the relative recency of the horrors of WW2 and the American GHQ occupation of Japanese should also be thought of.
the author also references other Japanese and Western opinions/studies on Japanese theatre, so the text feels like it fits within a tradition of scholarship and isn't just some guy's opinion.