This book warms a weird part of my heart where a stiletto heeled old man collects various monsters and puts them into a zoo for the insane. If you don't love this book, then I don't love you.
What's not to love?
Original monsters -- every. damn. one.
Compatible with your Old School Stuff (and your New School stuff).
The monster entries are inspired with the addition of the traits: As Big As, Smells Like, Sounds Like, Favorite Pastime, Turnoffs...
An adventure that doesn't take itself (or you) seriously.
If you're looking for a diversion from your standard fantasy, give ole Grandpappy a try. And if you're like me, pick and poke the things out of it that you can use elsewhere, or plop it down whole cloth in the middle of your mega-dungeon.