First, a slight word of warning: this book is effectively a 2nd Edition of an earlier book by the same authors, called 'Horror: The Definitive Guide to the Cinema of Fear'. However, even if you already have that book it's worth getting this one. Where the earlier book ended in 2005, this has been brought bang up-to-date to cover the best of the genre's offerings in more recent years (the last films to be looked at in detail are 2013's V/H/S and Mama). Other parts of the book have also been tweaked here and there to bring it up to date.
As for the book itself: I have read pretty much everything there is to read on horror films. I have "tried the lot", as it were. And I can categorically state that this is the BEST book on the subject I have ever read. Whether you are a seasoned horror fan & scholar (like me), or simply looking to broaden your appreciation and viewing of this most versatile and fascinating of film genres, this does the job. You can sit down and read it at length, or equally easily jump in and out of it at random points. The authors' knowledge of the subject - and, crucially, their ability to convey it accessibly yet intelligently - is second-to-none. I have found myself discovering many great horror films as a result of a mention of a film not covered in detail here, but mentioned in passing as a key influence (or descendant). It's also wonderfully global and even-handed, giving an appropriate amount of emphasis to country's key to the genre's evolution (Germany in the days of silent cinema, for example), while being sure to include the key works from country's not renowned for their horror output.
In short, forget any other book on the subject. This is the only one you need. BUY IT!!!