Sandman and Neverwhere are the works that really drew me to Neil Gaiman. Everything since then has been enjoyable, but not quite as magical as those, for me. Except for American Gods. It's not a popular opinion, but full disclosure, I really disliked American Gods. So, if you loved it, then maybe my take on this book isn't something you'll agree with either.
I thought it was OK. I was drawn in, and interested in the story. I was entertained. But ultimately, I wasn't moved. It didn't have that magic that I remember. I thought the beginning moved too quickly. There was action before I had gotten to know the characters, and that generally makes me not care a great deal about the action. I almost gave up, but since my book club was reading this book, I pressed on. I am glad I did, because my enjoyment grew.
I don't feel able to say a lot about the specifics in this book, due to spoilers. Like most of his work, it deals with folk lore, which is quite enjoyable. Like, say, The Graveyard Book, the main character is a young boy. Like Neverwhere, there is a girl who introduces the boy to a world he didn't know existed. To be honest, this story seems pretty much piecemeal recycled concepts from previous works.
Still, it's not bad. If you enjoy Neil Gaiman, you will enjoy this. If you haven't been impressed with his last few books, this one isn't going to change your mind.