Hewitt himself advises from the very beginning: his purpose isn't to tell a real biography of the band, instead he offers a guide "made from fans for fans". As he also tells in the book's introduction, Armando Gallo (photographer, friend and biographer of the group in it's early years) has already published a few works covering the personal and musical development of Genesis. Therefore, "Opening the musical box", could be taken as a "Manual for Genesis fans" in which you can find a small biography full of anecdotes, a really complete discography, dates of the tours with their different set-lists as well (all this referring to the band as well as the solo careers), also there is a list of the fan clubs, another dedicated to the official and "bootleg" material that's been released through the years in different formats. In spite of these great efforts some may find too obsessive to make an analysis of the tour programs
Obviously, in these days of swaps and shopping in the Internet, this book is extremely useful, it lets the collector (whether he is experimented or not) to know what is he getting and if it's worthwhile. Maybe it's utility in this camp makes the book less vital in other areas. Although we've been warned of the fact that this is not a biography, it is too quick in the 50 pages dedicated to the history of the band (it covers until the release of "Archive 1"), even if there is plenty of anecdotes told by the members of the band in their interviews with the fanzine of which Hewitt is the editor (The Waiting room). But at a very few moments there is a explanation of the songs, their meanings or process of writing. Anyway, is gratifying not to have to read again of Phil Collins' or Peter Gabriel's marital problems.
Another positive point of this book is the covering of the individual solo careers, especially in the case of those that's had less presence in the media (like Tony Banks or Anthony Phillips), but in this case the length is also a problem, only 6 pages dedicated to each solo career.
As stated before, a guide specially interesting for those who want to explore the incredible amount of material that's available of one of the most important bands, not only in the progressive genre, but also in the world of music.