As far as the story itself, I think it calls to mind Outside Over There by Maurice Sendak or Labyrinth--another story of an older sister going to rescue a young sibling, kidnapped by otherworldly creatures. Although in this case, the young brother is kidnapped by crows. Still, there is plenty of magic and enchantment once Prue, the elder sister, follows her brother into the Impassable Wilderness, the magical forest of so many fairy tales.
Her not-quite-friend Curtis follows along and has adventures of his own. The two soon discover that there is much more happening in the Wildwood than one missing little boy, and find themselves placed where they can effect events.
Honestly I found this book a struggle to get through. It was way too wordy and there was not nearly the depth I was hoping for in a book over 500 pages long. Meloy doesn't have the gift of description that some children's writers do, and even as an adult I found myself rushing past the lengthy descriptions of everywhere the children ended up.
Even so, the plot was entertaining enough that I wanted to finish the book (even if I did speed-read through quite a bit of it).
My main problem with this book was the parents. It's tricky to have a child protagonist if there are adults in the picture; I think that is why there are so many orphans in children's literature. But the parents in Wildwood are alive and well, and, it turns out they know more about what's going on that they're letting on. Prue eventually discovers, after she returns home (in the middle of the book), that her parents made a bargain: they couldn't have children, so they made a deal with a woman from the Wildwood, that if they ever had a second child, that child would belong to her.
Now, in fiction, I can see a bargain like that being struck. After all, they don't even have ONE child, how likely are they to have two? What I could not get past was the parents' attitude, when they discover that the reason their children are missing was that the daughter went to find the baby, and found out that he'd been taken by the women they struck the bargain with.
And they shrug their shoulders and give up. And Prue says she's going to get him back, and they discourage her, saying that the three of them can be a happy family. I find that utterly beyond the realm of believability. Whatever other charms Wildwood may hold, that section in the middle ruined the book for me.
That may not be a factor for other people. Overall, I can't really recommend this book unless you are a hardcore Decemberist fan (the author is one of the band members) or if you... hate parents or something. The illustrations are gorgeous, and I hope we'll see more of Carson Ellis's work in children's literature. If you see the book at the store, I'd encourage you to pick it up and flip through for the lovely inserts.