If you are a Magus delving into the murkier corners of the supernatural, you expect to find a few odd critters hiding in the shadows longing to send you gibbering back into the light... well, here's a neat little collection all ready for the GM to do his best to meet your expectations.
The really nice thing about this collection is the way in which lots of features are introduced and explained, perfect for those GMs who like coming up with their own monsters (or adapting ones they've read or heard about, or seen on TV) - you can either mix and match these features or, having been shown how they are put together, come up with your own. Apart from fiction, some of the pseudo-documentaries investigating the paranormal can be fertile spawning grounds for ideas: now you have some tools to turn neat concepts into full-blown monsters that 'work' within the rules as well as sound suitably creepy when you describe them to your players.
That aside, the actual creatures have a lot of plot potential too! It is easy to build an entire adventure in your head as you read through, say, the entry for the Court of the Yellow Ribbon Cultist... and startle your players, never mind their characters, when certain key features involving said yellow ribbon are revealed. (No, I won't say what, I know some of MY players read my reviews!).
An interesting resource for any game that dabbles in the supernatural, and particularly useful if Glimps The Beyond is your system of choice, although it ought not to be too hard to adjust game mechanics for your chosen ruleset.