I just finished reading this book to my 10-year-old sister; I read it myself at probably the same age. I'm experiencing what I often do when I reread good children's books - it's a lot darker and more intense than I remember! At the time my response was - and what my sister's response is now - "it's a cute book about a mouse who saves a princess!" But now, I'm realizing that it tackles death, family betrayal, and abuse and continuously made me question if it really should be a kids book. 

I think, like many kids books, this is what it's supposed to do. Bring kids into its world, charm them, and teach them about humanity, while leaving adults wondering if their kid will be okay. (Does that make sense?) Think re-reading Harry Potter as an adult - you didn't remember all the death stuff being quite so dramatic, did you?

Besides the somewhat dark subject matter, it really is quite charming. The author's narration is very unique and constantly asks the reader things about the story, which my sister was happy to answer out loud! (ex: "And what, dear reader, do you think happened next?") The pictures are absolutely lovely (~1 per chapter). 

I would definitely recommend for 3rd-6th graders who like fairy tales, empathize well, don't need action on every page, and can handle scary plots.