I read this book because I inherited a curriculum in which this was an extra-credit assignment (read and write a book report on...). I'm glad I read it, because now I know that this is a wildly inappropriate book for a college freshman to read. Sure, it does reinforce a lot of what was taught in that course, but it does so on the intellectual level of someone who has advanced degrees and reads a ton -- so not today's average college freshman. It's also somewhat dated, of course, although that in and of itself has some charm, if you're interested in what people thought of music and its future in the 1030s-1950s.
All that being said, Copland does manage to put some things into words better than most, so I may refer to this again when preparing lectures for non-majors.