This answer contains spoilers… (view spoiler)[There is no graphic violence or giant monsters, but there are some things that might scare younger children. On the other hand, they might not. Here are the scariest things as I remember them: The girls' father has gone missing. Snow thinks he will come back but Rose doesn't think he ever will. They are chased by bandits. They are chased by wolves but are saved by a huntsman. They meet a rude little gnome whose legs bend backward. Their friend, a boy named Ivo, find their father's knife with blood on it. Ivo later goes missing in the woods. In the final scene, Snow is turned into a big by the gnome (who was the real villain all along) but they are saved by the bear. There is a happy ending, and it turns out all the people who went missing had just been turned into animals. With the gnome gone, they all turn back. (hide spoiler)]
Orinoco Womble (tidy bag and all) It's not a children's book. It depends on how mature your kids are. There are things that would go straight over a little child's head, but there's a lot of running away from bad people/animals that might scare them.
This answer contains spoilers… (view spoiler)[I read this to my 4-year-old, but I did skip a few parts. The story begins with two girls who believe their father is dead and they are dealing with the fallout of that in their own ways. If you are not comfortable exposing your children to the idea of death, then this might not be the book for you. There are also ominous supernatural elements that can be somewhat frightening. At one point, you are led to believe a main character has died, which might be hard for young kids. However, it is a lovely story that is well-written with excellent poetic elements that are still accessible to a younger audience. Both I and my daughter enjoyed the story. (hide spoiler)]