This is a book that doesn't just come along once in a lifetime or once in a century, but once in two centuries. To my knowledge, not since William Hershel created his catalogs between 1786 and 1802 has there been a comprehensive volume written by someone who has personally observed each and every one of the Hershel objects (and like Hershel, without the aid of electronics). Add to this the fact that Mark Bratton is an "observer's observer" who knows how to organize an observing book in a logical, straightforward manner. No organization by RA and Dec. here. The book is organized by constellations, which for most observers, is the way they think of the sky.
The illustrations are also organized in a useful way. Instead of filling the volume with gorgeous Hubble images (which the observer at the eyepiece will never see), the illustrations are either DSS images or (most happily) sketches done by the author himself. At first blush, you might think it would have been nice to have an illustration of each of the Hershel objects, but who would want to buy a multi-volume set that weighed seven pounds just to see hundreds of pictures of elliptical galaxies. For the most part, the illustrations chosen detail areas of the sky that have several Hershel objects in the same field. This can be extremely helpful in the field.
Anyone who has had the pleasure of observing with Mark can tell you of the animated way in which he describes even the most mundane of the Hershel objects. The fact that he has personally observed each object produces much more accurate descriptions of their visual appearance, than someone who is extrapolating from a photograph what "should" be visible in the eyepiece. The fact that he includes his own observation notes alongside those of Hershel is especially helpful. On an observing trip with the author, I was able to see several Hershel objects, which would otherwise have gone unnoticed, based on his meticulous descriptions of them, from memory.
With the advent of go-to scopes and digital setting circles, it is unlikely that there will ever be another human being who accomplishes this herculean task, let alone putting it into a very well organized and readable book. Every other volume I have seen on the Hershel objects covers at best only a few hundred of them. This is really the definitive reference for the entire Hershel catalog. It is a long awaited and very satisfying addition to my astronomical library, and more importantly, just picking it up and glancing through it fills me with an intense desire to go out and observe.