Most of the book felt stagnant but there are pockets of action that didn't quite work. The children, used to running amok on their adventures for the last two books, are suddenly chaperoned and yet continue to lead the efforts to address world-scale problems rather than have adults step in. They instead seem to be patiently waiting in the wings for their moment to step in and comment upon the children's work instead.

The main antagonist devolved into a characature in this story as well. Her previous tretchery as a long-time librarian stealthily working for her own aims is mentioned, but now she's cartoonish instead of subtle. Oh, and the entire plot revolving around the Motherbook is diminished and then basically forgotten despite it's build up in the last two books.

The actiony ending could have been stronger as well. This author is very good at writing character pieces, dialogue, and introspection, but seemed less practiced at large scale action. There should have been a greater sense of tension, beats that pulled the story forward quickly, and descriptions of the daring action. Instead each build-up of threat was immediately balanced by telling us about the counter plans already in motion. Choatic scenes of fighting are interrupted by dialogue without urgency, and the heroic actions are generically referred to without zooming in.

Overall this was a bit of a disappointment after the strength of the first two books.