I think this is Baldacci's first entrance into the YA market. With a "fifth grade" reading level and interest level of fifth through 9th I think the writing is a little challenging. Learning Baldacci's new terminology for the world of Wormwood was a bit complicated. However, it was well worth the effort involved. Our heroine and hero are well crafted and the situations facing them nuanced and engaging. The "Wugmorts" (citizens of Wormwood) are fearful of the surrounding "Quag" and the monsters lurking there. As a result they are limited in their means and their visions of the world.
Vega Jane, a 14 year-old, is not quite so fearful and over the course discovered her destiny to escape Wormwood and venture into what is likely to be a series of adventures that will lead back to Wormwood (just my prediction here). The portraits of small-minded and fearful citizens in Wormwood and the effects of repression provide interesting discussion of contemporary issues facing our world. I don't want to influence your own interpretations---but I found fertile ground for considering contemporary issues.