There are really only two problems with the Mammoth Book of Slasher Movies by Peter Normanton. Unfortunately, they're both really huge. (Perhaps they're the Mammoth Problems with the Mammoth Book of Slasher Movies? No? Okay. Please yourself.)
The first isn't so bad--the author includes a number of horror movies like '28 Days Later', 'Living Dead at Manchester Morgue', and 'Night of the Living Dead' that aren't actually slasher movies at all. They're zombie movies. Now, I love a good zombie movie as much as the next person, and probably significantly more than the next person depending on who the next person is. But a guide to slasher movies should be aware of what a slasher movie is. In specific, a slasher movie is one that foregrounds the persona of the killer or killers with an intent to make them distinct or unique in some way. (There are also a number of cannibal movies, which kind of blur the line because usually it's an entire group of people acting as the cannibals, but I can at least forgive those because often the cannibals are recognized as unique and distinct individuals. Zombie movies, though, are about a faceless horde.)
This means that there's less space for analysis, because the book is stuffed full of movies that don't belong in it. It also means that the sequels are footnotes at the end of each entry, which is a shame because frequently the tone of a slasher franchise changed over the course of each entry, and it would be worthwhile to look at the way that (for example) Freddy changed from being a grim and vicious child molester to being a malevolent trickster-god, or the way that the mythos of Michael Myers got progressively stranger with each installment.
Worse, though, was the decision to file the movies alphabetically with an index at the back showing their chronological progression, rather than filing them chronologically with an index at the back showing how to find them in alphabetical order. This is absolutely gutting, because what analysis there is of the movies focuses on the way the genre developed as different filmmakers explored the motifs and translated the idea of the Italian murder mystery known as the giallo into American horror...and how a new generation took a genre that had become trite and formulaic and began experimenting with that formula.
So you can imagine how the book is impacted disastrously by having hugely influential films like 'The Texas Chainsaw Massacre' in the back of the book under 'T', while something like 'Hostel' is about a third of the way in. Any attempt to derive meaning or insight gets lost in the random shuffle of movies, and the book becomes a confused recitation of random details without context. I really wanted to like this book--Normanton clearly knows his stuff, and there's a lot of obscure movies in here that clearly illustrate his ideas about how the genre evolved. But the lack of organization turns it into something of a slog. Unless they fix this problem in a revised and updated edition, I wouldn't spend your time or money.