Stop me if you've heard this one before.
A girl and her parents move into a new house. The girl's parents don't really pay much attention to her, and she gets bored and starts exploring. Along the way, she encounters an alternate world, and a talking cat companion. It turns out there's an evil involving the alternate world that she needs to do something about.
You can modify some of that sentence to add a plural to "world" and "companion", but I basically described the gist of the plot of Coraline
as well as "The Books of Elsewhere: The Shadows". It even contains some elements of exaggerated character humor as well. But it does take on an identity of its own after a while, and becomes an entertaining book in its own right.
The alternate worlds concept has some interesting ideas applied to it here. The worlds are reached by climbing through paintings, and the paintings tend to be themed after the sorts of things that paintings are often themed after. Imagine if Norman Rockwell paintings, or landscape paintings, etc., were literally portals to entire worlds. Well, the worlds themselves become things such as an abandoned town near the woods, or a bunch of carpenters who have literally nothing to do but build things, and are so surprised to see company come in that they'll talk forever. It must be boring living in a painting themed after carpentry.
With the diversity of the painting worlds, that means a diversity of moods. Besides the levity of the conversation in Carpenter Land, there's also an evil villain responsible for these paintings, who is trying to Take Over The World
, and things do get dark. And there's the element of conspiracy - can Olive really trust the cats? The boy she rescues doesn't think so.
The cartoony illustrations are a nice surprise, and I really like how they add to the light-hearted fantasy feel without taking away from the darker elements. Plus, they help make the implausible more plausible in context. The three goofy talking cats fit into the story better this way.
I'd call this a 3 out of 5 book; entertaining but not great, but I enjoyed it.