There is quite a spate of books discussing the dark materials trilogy of Phillip Pullman. Many of them are serious academic articles concerned with how the book delves deeply into religious, and philosophical arguments.
This book is at the cheaper end of the market, but in terms of what you get for your money I would consider that I have paid dearly for it.
It is without doubt at the lighter end of the spectrum academically also, while I can understand that not everyone wants to read a thesis, I also think that they should be treated with a little more respect than this book shows.
I was significantly disappointed with this book, it deals very, very lightly indeed with the issues it brings up from the trilogy. For me it presents little more than a commentary on what happens to the characters overall, and if you've devoured the books as thoroughly as I have, then you'll find this irrelevent re-hashing.
It was also poorly written, although you won't find 'mistakes' or weak structure as such, I found it blandly presented; comment, reference, comment, reference and so on. It had no style or personality, and could have been written by anyone with a passing interest (though not a great one) in the dark materials.
I kept searching for instances of greater analysis and depth within the book (which doesn't take long - it is a very short text) but to no avail. There are chapters on Phillip Pullman himself, and on the book's reception, but these are a couple of pages long between them and certainly don't make up for the dearth of interest in the other chapters.
If, perhaps, you are new to the books, or just thinking about the myriad of concepts, as well as the intertextual facets of the trilogy, then this book will be useful. But it is at best a starting point, I would advise searching the site for other, better written articles or books; there are certainly many to be found.