This book is the first of the series and has long been something I love. Bishop is an utterly brilliant world builder and both world and character are important, weaving together to create something truly beautifully layered. The characters are nuanced, even the main ones having flaws and making errors, and the 'bad' characters are fantastically built because you can see why they feel the way they do. This has become my favorite paranormal setting. 

Overall it’s simplistic and cutesy, despite some darker themes. There’s a lot of repetition, and the worldbuilding is lazy. Characterization can get lazy also. For example, POV characters in the series  all describe the ponies with the same words: grumpy faces, barrel chests, clompy dinner-plate sized hooves. No matter who they are or where they’re from they all eat dinner on a plate the size of an elemental pony’s foot, apparently. 

I wouldn’t consider this book to have a diverse cast, unless you count the many types of Others as diversity. Among the humans it’s almost exclusively cishet white.