Although this looks like it should be a version of Hansel and Gretel, it's actually a retelling of The Snow Queen. (Although it does have some Hansel and Gretel-esque moments.) In fact, the story borrows from several other traditional folktales, but mostly is about Hazel battling through to free her friend, both from capture and from the emotional danger he is in.
I loved this one. Considering that the story starts in a modern setting and manages to find it's way into the Dark Forest of fairy tale lore (and back again), I found it all to be believable by the time Ursu worked her magic.
In addition to the story, there are several inset art pieces, and they are just lovely:
Although the bits and pieces of stories that cross Hazel's path aren't as predominant as in some mashups, they were essential to the mood and atmosphere of the book. These aren't princess stories or happily ever after stories, and they lend the sense of danger to her quest. There is also the danger that she herself will lose her way, and simply take up residence in the imaginative forest without bothering to save her friend or return to her real life. (And I really appreciate that the symbolism of this is purely symbolic, not implied to be the "true" version of events. She's not dreaming or pretending!)
This is a quick read for adults and perhaps a somewhat challenging book for middle grade students, who won't necessarily recognize the folklore than Ursu is drawing on. Even so it's a very satisfying challenge/success story, and may be a good introduction to the width and depth of folklore.