Horrors of the Weird West is basically a monster book for d20 and specifically Deadlands d20. It's softcover, 128 pages and priced at $20 and is pretty much the same physical quality as most Pinnacle products (that is to say, a bit on the cheap side). And like most Pinnacle products, it's got large margins and somewhat large type (and like Deadlands d20 products, recycled art from original Deadlands d20 products, though many I hadn't seen, so it's not too bad). (This is what kept me from paying full price for it at a store - I got it used for $10).
I'm not going to go into each individual critter, but as a general overview, it's largely a combination of historical/mythological/folkloric critters and beings, combined with some from Pinnacle. There's a lot of them - too many for me to count easily, though the back cover says 100.
As D&D takes many of it's monsters from real world folklore and mythology, there is some overlap. Doppleganger, Vampire, Ghost, Mummy, Zombie. But Pinnacle goes as far as to include several varieties of most of these. For instance, there are 8 different types of vampires (plus a specific vampire, Dracula), and around 10 sorts of zombies.
Besides that, things that caught my eye were the Chupacabra (or goatsucker, though in this case it's renamed a bit), both Frankenstein and his monster, and Springheel Jack (which did in fact make some appearances in the US, and is actually possibly related to the so called "Monkey-man" of India reports a couple years ago), and an Aztec style mummy.
There are also many things from the Deadlands universe/setting. Dr. Hellstromme's automatons. Civil war ghosts. But not too many, and many, like the automatons, can be transferred to a non-Deadlands game pretty easily.
The d20 stats are generally fairly well done. I've only used a handful of these critters, but the stats seem okay, and CRs seem about what they should (a few maybe 1-2 too high, a few 1-2 too low, but I haven't noticed anything really wacky, like in a certain other companies products). Nothing really major sticks out except that many of what probably should be templates (like the various vampire types) are in fact regular monsters. And advancement seems a bit oddly done for these.
If the vampires were done as templates, I probably would give this an A-. But as it is, it gets a B. It's worth picking up if you run Deadlands d20, and quite possibly if you run another sort horror d20 game or one set on earth, like Cthulhu d20 or even d20 Modern. For instance, one episode of the classic TV show The Night Stalker involved an Aztec Mummy of sorts (and starred the legendary Erik Estrada. Alas, no stats for him).
