I don’t think Neil Gaiman is capable of writing a bad book. The imagination and creativity that went into this story is insane - from the life-sucking Velvets, to the Earl’s Court in a subway car, and the Angel Islington in the British Museum - everything was so well thought out and whimsical. The characters travel to different places constantly, each with their own surprises and special kind of magic/inhabitants. It was so incredibly fun to follow the characters through each destination - the floating market, the abandoned hospital, Down Street, Serpentine’s home, as well as the previously mentioned places.

I liked the darkness of the story with death not being uncommon, but the cheeky humor mixed into the writing. Richard was an endearing main character, even if a bit of an idiot, but a lovable one.

I appreciate that the exposition lasted as little time as possible to allow the reader to immediately jump into the action with Door being pursued by Mr. Croup and Mr. Vandemar, who are actually extremely frightening. All of London Below is a nightmare to be honest.

The end is kind of frightening to me in that Richard Mayhew chooses to return to London Below, after successfully returning to his old life, but quickly becoming disillusioned with how confined it is and how everyone there is bound by expectations.

Finally, a couple criticisms. The first is that I wished more emphasis and build up was done for making Richard the beast slayer. There was a little foreshadow but I didn’t feel that there was nearly enough for how big the task was made out to be. Second, this isn’t necessarily a bad thing, just an observation: the entire time Richard is in London Below feels like a climax, which makes the actual climax not feel as climatic. There entire thing is exciting but the final battle does feel less important due to constantly being on the edge of my seat.

TL;DR
Whimsical, magical, nightmarish but in the good way. I have never read a good with this amount of creativity.