There are not many books like this. The authors have set themselves a difficult task and succeeded spectacularly. If you only invest in one or two books on the subject, buy it! If you fancy a small library, you may just possibly think you don't need it...
Photographing Garden Wildlife covers everything; all from first principles (check Amazon's LookInside feature): floral and faunal ecology, gardening for wildlife, photographic equipment and functionality, subject matter, picture composition, and image processing. In little more than 100 pages, half of which is occupied by gorgeous photos.
The writing is succinct, salient and highly readable. So you'll find a broad range of nuggets of useful advice, but no in-depth exposition of any one subject. The title per se covers roughly one third of the book; and the photos are mostly inspirational rather than integral to the text.
If you're au fait(-ish) with any of the topics, then don't expect anything new. It's not reasonable to demand a comprehensive book of this size be profound too! And it doesn't seek to be radical. But consider the topics you're less familiar with, or its visual luxuriance.
One fair criticism is: why isn't there more? More creatures, more plants, more kit, and more idiosyncratic approaches could all have been included with advantage. A more-advanced example or two would perhaps be just the thing to round off each section... Let's hope the publisher decides to produce an expanded second edition.
Lastly, don't approach the book with any mistaken preconceptions. It's a set of straightforward tips covering the whole business of capturing beautiful images of relatively-common wildlife subjects.
It isn't an erudite photography manual, and there's nothing on detecting or spooring rarer species - so it won't help you join any David Attenborough expedition! And it's nothing to do with creative arts - so don't set Garden- or Wildlife Photographer of the Year, as your targets!