Although I'm at best a mere dabbler in wheat beers, I own it and think it's worth having. I suppose it depends upon what you're wanting to get out of it. If you're looking for a recipe-heavy book or a book that lists "this one easy hack" style tweaks, perhaps you won't rated it as highly.
Hieronymus structures the book around the primary wheat brewing traditions of Belgium, Germany, and the USA. He builds his narrative from an impressive series of interviews with well-regarded wheat beer brewers from each tradition. While there are plenty of detailed descriptions of techniques and methods, I think it's best to think of Hieronymus' goal as being more about the process of going from recipe creation, to grain, to glass, rather than silver bullet techniques that will instantly turn your flabby hefe into a the greatest beer ever made. He also allows the various brewers to demonstrate their differing approaches in terms of techniques and processes. This isn't a manifesto on the one true way to win beer contests. Rather, it's a thoughtful look at how various brewers think about wheat beer, structure their processes, and employ techniques to create world class wheat beers.
Hieronymus is a pleasant, easy to read writer. He builds each of the main sections of the book around the history of each wheat beer brewing tradition. As a Gen-X refugee from Portland, OR, I found the section on Widmer Hefe fascinating and fun. Likewise he does a great job of unpacking the myth, determination, and outright ******** that was the amazing Mr. Pierre Celis. I've read many versions of that story and I think Hieronymus delivers the clearest and best telling.
All told, it's an easy, enjoyable read that intertwines the history, process, and techniques of wheat brewing. It can be a bit frustrating when you have your brewing software open and you're trying to use it as a technical manual, but it does have an excellent index so it is still useful in this context. I've had the book for several years now and during that time it has made a few return trips to my nightstand. It's a pleasant book to reread.