This is meant to be an informative, non-fiction work. It is riddled with blatant misinformation, from simple facts to entire narratives. You will actively handicap your knowledge of werewolves by reading this; if you want an accessible work on werewolves, read Adam Douglas' The Beast Within: A History of the Werewolf.
We spend a good deal of the book repetitively haranguing over demonologists' texts, where Woodward demonstrates a complete inability to critically read anything put in front of him; all events happened as they are written, all authors are taken at their word - he believes all the witch trials involve people who did commit the murders attributed to them in the manner described, the question merely being one of whether they are actually werewolves or not.
Woodward is confounding here. First we're told, definitively, that they're simply suffering from the titular werewolf delusion - in his terms, a form of hypochondria where the patient irrationally believes they've turned into a wolf. Then, half way through, we swerve into a measured explanation that theosophical spirits exist and that werewolves are obviously demonstrating astral projection, except they're feeble-minded people who have their souls snatched by evil spirits and manifested as wolves, wolves being the literal embodiment of evil (seriously, this book has a near-hysterical attitude towards wolves); this is given the definitive explanation. Then in a short chapter we're told that, naturally, werewolves are almost entirely people who suffer from rabies, and that this completely explains the phenomenon.
The fact that none of these make any sense is irrelevant to Woodward.
When we deal with other topics - folklore, mythology, history - Woodward does not cite his sources, except for extensive quote-mining of O'Donnell (a fiction writer) and Summers. Almost all of this is taken from Baring-Gould and Summers, except Woodward pretties up what he takes with invented elaborations and schoolboy errors, jumbling it all into muddled analyses and conclusions.
Bizarrely, in the penultimate chapter, Woodward presents an anecdote he heard "on a motoring holiday in France", then paraphrases a story lifted directly from Boguet. He actually does this several more times, presenting bits of folklore obviously taken from Baring-Gould as if he travelled around Europe and heard them personally. This is somewhat fitting, because at this point you'll have been subjected to many instances of Woodward unsubtly puffing himself up with all the "people" he's "contacted" and who have "contacted" him back in the research of this book. I imagine that's why he doesn't cite anything - throughout, he clearly tries to make this book seem like a feat of research, when he's just riffing on the same few books who've done all the hard work already.
There's one final, and equally bizarre, problem - a good deal of the images have incorrect captions. I don't know if it's sloppiness or inventing information that Woodward wasn't privy to to fill the book with learned captions, but it's worth pointing out.