Conversely, it is not completely "basic" either. In fact, my daughter loves her books so that she reads everything, including things much more complex.
I found the story very imprint of American culture, with very present money terms, when the hero must be an "agent" to write his book ... Well, not very childlike but not stupid either of raise the economic realities.
For a child between 7 and 10 years I would say.