The plot for Zod Wallop is always surprising, sometimes funny, but often the situation is dark. The world of Zod Wallop sounds grimmer the more we learn of it. Harry wrote the book when mourning the death of his daughter, it was never meant to be published. It is certainly too dark a book for normal children.
Spencer can really write an entertaining book. When reading along, I often came upon an impressively written paragraph - more than great characters and a bizarre, entertaining plot, Zod Wallop also contains a quite a display of wordsmithing. It's like reading a Mark Helprin novel: the words are just as entertaining as the story.
The characters are also well defined portraits. Each of the lunatics from the asylum has a well defined personality. Not all the bizarre people from the asylum were the patiences there. The bad guys are deliciously evil. Characters, writing, plot - Zod Wallop has it all. This is an entertaining read.