This book leaves me a bit puzzled as to how characterize it best. It's full of some of the liveliest and most engaging writing about the development of the American tongue, and at the same time it's just riddled with errors of etymology and history. Bryston relies on some of the classic references - Mencken, Flexner et al- to the extent that he has never checked any of the newer references. Hence he still repeats the etymology of "OK" as the mid-19th century "Oll Korrect", despite the more recent scholarship that points to a great number of cognates in West African languages as the more likely source.
His historical treatments are similarly spotty. He notes at least one Native American document that appears to have influenced the language of the Constitution, but is blissfully unaware of the numerous state constitutions and articles of confederation and other historical documents from which ideas and language were lifted. His reading of the first and second amendments are laughingly ahistorical.
In discussing the songs associated with wars, he remarks that unlike the Civil War and WWI, WWII had no memorable songs! He also states that "bought the farm" is a phrase from the Vietnam War, something that would surprise anyone who's ever seen a film about the RAF in WWII. (I believe the phrase is actually a bit older than that). And he thinks "pilot" came from early aviation, when it's a very old nautical term.
The creative etymology he gives for "hacker" along with his 1975 citation is an amatuerish guess; the actual etymology is very well documented in the popular book "Hackers" by Stephen Levy- it first attained popularity as a reference to a technical accomplishment in the MIT Model Railroad Club long before 1975.
These criticisms just scratch the surface; as I read the book, I filled page after page with similar errors. And yet, for all these errors, it's still an engaging and enjoyable book. Read it and enjoy it- but be extremely cautious about citing it. If you want an interesting and accurate book, read instead "English: Its Life and Times" by Robert Claiborn, a lively and yet scholarly history of the language,, from origins to modern useage.