The book purportedly tells the story of classical music in America, how Old World traditions were transformed and revitalized, and how concert music came to interact with popular trends. I flipped to the chapter on film music, and to his credit the author makes some very defensible claims for the genre, at it's best, as being the equivalent of incidental music written for plays, or even singspiel music composed by Purcell, Telemann, Mozart and others. (Opera would be a little more of a stretch, since the film composer cannot ordinarily manipulate the "libretto" -- in this case, the screenplay -- where he would be able to, in the case of the genuine article.)
However, despite these commonsensical claims and pleas for critical tolerance, the author doesn't seem to know very much about his subject matter. He's got the "sense" right, but his facts are all wrong. I read maybe a dozen pages and, over the course, found at least four factual errors. He claims that Erich Wolfgang Korngold quotes thematic material from his score to the "Sea Wolf" in the slow movement of his String Quartet No. 2 (when, in reality, it is the Quartet No. 3); he claims the same composer's Symphony in F#, while reminiscent of his film music, is comprised solely of original material (when, in fact, the melody of the slow movement was lifted from his score for "The Private Lives of Elizabeth and Essex;" and the finale uses a motif associated with the Maria Ouspenskaya character in "Kings Row" -- something I have never seen mentioned by any annotator); and that Dimitri Tiomkin wrote the score for Alfred Hitchcock's "Spellbound" (it was actually Miklos Rozsa, who won an Oscar!). On top of it, I suspected his claim that Victor Herbert wrote the score for D.W. Griffith's "Birth of a Nation" was equally false, but THAT I had to double-check. The score is mostly a hodgepodge of pre-existing classics, like "Ride of the Valkyries," anyway. As it turns out, I was right -- it was written by Karl Breil. In any case, it's not my job to research these things. You'd think Yale University Press would hire a fact-checker.
Breil aside, I could have written the chapter off the top of my head, virtually complete, right down to the historical dates, and not made so many errors. I don't know if it was sloppy note-taking or faulty memory, but the book never should have gone to publication in this state. What if someone comes across this thing in a university library somewhere and takes it as fact? We'll have all these theses on film music that reiterate the heinous error that Dimitri Tiomkin wrote "Spellbound!"
For a good general survey of American music, you might try Wilfred Meller's now-classic "Music in a Newfound Land," or even H. Wiley Hitchcock's "Music in the United States." However, film music is a weak link in both studies. For that, I would refer you to "Film Score: the Art and Craft of Movie Music," by Tony Thomas. Thomas highlights most of the major composers, and many of them contribute in their own words. It's an interesting read, and you learn a lot about the unique challenges faced by the composer in Hollywood.