Chaos Walking trilogy and thus had no hesitation checking out Ness' newest book, A Monster Calls, inspired by an idea from Siobhan Dowd. However, this book has a significantly different feel and purpose than his previous novels, which makes them hard to compare.
First, though A Monster Calls is packaged as a novel, it's really a short story that, through large type, large margins, and many illustrations, has been stretched to two hundred pages. I don't think there's anything wrong with the length of the story, but it would have been helpful going in to know its format. There are different expectations for a short story than for a novel, and a certain absorption into the book that's not possible at shorter lengths.
In its style, A Monster Calls most closely resembles a fairy tale in which a hero must confront his demons to learn the truth about himself. The book's protagonist is thirteen-year-old Conor, whose mother is dying and who has a terrible secret he's unwilling to tell anyone. He's confronted one night by a monster that takes the shape of the yew tree outside his home; the monster will tell Conor three stories, and Conor will provide the fourth and final tale. The piece is a clear allegory, with the yew tree monster representing those aspects of the hero that he most wishes to hide from.
Ness does an excellent job of capturing the dark and stormy atmosphere of Conor's inner life. The accompanying illustrations, done by Jim Kay in smudgy black and white, powerfully reinforce the mood. There's a clear message in the end--that there is both bad and good inside us all, and only by speaking the truth of both can we be healed--which is brought home in forceful and moving way.
Despite all this, I wouldn't say the book really got under my skin (in a good way) or will have a lasting impression, completely unlike the Chaos Walking books. I can see it as a book an adult might read an (older) child--it's quite dark, but there's are elements that feel like they need to be shared to be understood.