With one more chapter to read, I think it fair to say that I've got the measure of this book.
As the three stars suggest, this isn't a bad book and it gives a decent enough account of the band and its pre-history. The problem is that it overly relies on a series of interviews and some very extensive quotations from Penny Rimbaud's previous publications. Often these sources are allowed just to stand by themselves, so sometimes Berger is only really present in the form of connecting phrases or paragraphs. When, however, he does add context or views on the political or social situation, the arguments are remarkably one-sided and often devoid of evidential support.
Chronology is also a problem, despite the chapter headings that ape Crass's own use of numbers (e.g. 421984 - four years to 1984). Future events are referenced before being properly introduced and so the less informed but interested reader is left struggling to understand what is meant. Berger is also an insider, who lived through much (all?) of what he discusses, so there's an assumed knowledge running through both the history of the band and the history of the UK at times.
The book is rarely critical (as I said, rarely - there is the odd moment, but they are few and far between) and lacks the depth and complexity of something like Jon Savage's England's Dreaming. The book is thus rather lazy, relying on access to those Crassers who agreed to be interviewed, rather than anything approaching research. That said, as a documentation, there's some really good material, but this certainly isn't a 'history' of the band.