Enormous, detailed, masterful, imaginative. Easily as fun to read as it is to use. This is one of the most impressive RPG supplements I've ever bought.
This is a book that doesn't waste time or mess around. It does exactly what a good supplement should: It goes super deep on its chosen niche, to the point where it serves as an seemingly-inexhaustible source for ideas and answers. Making a whole campaign from this book will still take a lot of writing and creativity on the GM's part, but there's an overflowing well of inspiration here if that's what you're looking for.