I love picking up these books and flipping through them, looking at new openings and reading the comprehensive but nonetheless insightful descriptions by van der Sterren. If you like that ‘tingle’ of exploring a new opening and want to have a book that can give you an idea of the nature (playability, style of play, sharpness) of any opening, this is the book for you.

And once you have fallen in love with an opening, you will eventually buy specific books on the subject anyway. This book’s section on the sicilian eventually led me to studying the najdorf, which has improved my play immensely.

Don’t expect numerous variations, it’s the prose that makes this book worthwhile. If you like studying hard theory, like big variation trees and completeness, this book is not for you.

Here’s a review from amazon.com that captures more (and is a better advertisement at the same time):

“By revbd (Ireland) – See all my reviews
This book is outstanding in every way (apart from the awful ‘FCO’ title) and provides substantial coverage of ALL chess openings. It addresses both understanding and specific moves and gives lots of unusually well written explanation. In addition it is, I think, superior to comparable alternatives. For example: Watson is far less comprehensive (despite 4 vols), has big gaps e.g. Petroff, and his coverage is both uneven and less practical; Djuric et al is far less deep (despite 4 vols); Collins, though good and comprehensive, is considerably shorter and less focused on understanding; Kallai, though good, is focused primarily on moves; Fine is hopelessly out of date and, in addition, not good. Sterren’s opening book is a marvel which makes shelves of my introductory opening titles redundant.”

i may well be wrong, but in my eyes such books are crap intended to take some cash away from poor chess enthusiasts that started playing chess as adults and never had some elementary help on how to study chess.

I hope you’re not suggesting I must buy the books myself in order to be able to properly review them In any case, I really cannot judge whether a book is worth the money for anyone but myself.

To try and answer your question, I’d say the book is worth buying if you’re interesting in learning about the basic concepts of chess openings, provided you’re not looking for in-depth analysis of concrete variations or have a good knowledge of the openings you’re interested in already. Watson’s series, for instance, does go deeply into particular lines, which makes it a completely different project in my opinion.

The question a potential buyer (!) (not someone who got a free review copy) faces is: Is the book worth the money? How does it compare to rivalling books?

Apart from the title, I’d say there is barely any similiarity, that’s why I didn’t think a comparison would be useful. Still, yes, all these ‘CO’ books try to cover all opening theory in a concise way, so there’s your similarity, but they do it very differently.
ECO was a real encyclopedia, with the well-known trees and branches of variations as in the ancient Bilguer. NCO has the same setup, but already contains more explanantions, as does BCO. ECO, however, was a much larger project (if I recall correctly, it consisted of 5 volumes.).
FCO has another approach altogether: there are virtually no variation trees, only explanations. Also, the author cuts off the lines in a much earlier phase of the opening theory than the other books do, as is shown in my examples of the Marshall and the Gothenburger. The explanations are very good, as I tried to show, but of course a club player would also need a lot of concrete variations, especially if he’s going to try the Marshall or the Najdorf! So I think FCO is a very useful addition to other, more variation-oriented, opening manuals, but I still think the book is rather intended to make players enthusiastic than to make them more successful.