Simply put, if you buy only one monster book for your OSR game, it should probably be this one. It has most of the monsters from 1e, as well as lots of new creatures and variations. And unlike so-called "modern" monster books, the stat blocks are not the length of the tax code with a raft of abilities, exceptions and conditions to keep track of. Plus, there's a picture for every monster as well as a mini encounter or adventure hook. These are great for inspiration, side quests, or even to use as interesting random encounters. And there are many clever pop culture references worked into the encounters.

The only real downsides are that the images varey somewhat in quality and because they try to keep it one monster per page, there's often a lot of white space. So they could have added a bit more fluff to the text. But in a book that already runs over 500 pages, perhaps less is more in that respect. And to be honest, this black and white artwork suits the book better than the color artwork they've used in supplements to Tome of Horrors Complete, which should be the second OSR monster book you buy. With those two massive tomes, it's hard to see you ever needing another monster book. My only regret is that I waited too long to buy this so I was only able to get the pdf. Still hoping to snag a hard copy somewhere.

Swords and Wizardry Monstrosities is a new monster book. New in that is newly published, but some of the monsters we have before either in the SRD or other books. That though does not detract from it's value as this is a 560+ page book since in addition to that there are some new monsters. The cover is very evocative of the old-school (pre 1980) covers. I love this cover. There is much in common between this book and The Tome of Horrors. Each monster is given a page of stats, description and a plot hook. While ToH used some recycled art, this all seems to be new art. Even Orcus (which we now have 3 listings for) is new. Actually the art is pretty darn good and I don't mind the occasional repeat of a monster to see some new art. Honestly there is so much great stuff in this book that even with the occasional repeat monster this is still a top notch collection. If you play S&W then this is a great monster book to have. I am even going as far as to say it is a must have for any serious S&W GM.

After many Swords and Wizardry games, your PCs will slay every single monster in the rulebook eventually. If you don't want to bore your players with the same creatures again and again, you'll need Monstrosities. But if you think this book is just about 500+ monsters, you are wrong. Yes it's about monsters with details and good art but what makes this book great is every monster comes with a single pharagraph of short adventure or adventure hook. It's a great book for Swords and Wizardry GMs.