J.R.R. Tolkien wrote an essay, first given as a lecture, on Fairy Stories. Sadly, it’s rarely read. Which is unfortunate as it gives a fascinating insight on the idea of “fairy stories” as something meant for people in general – regardless of age.

Among those who still have enough wisdom not to think fairy-stories pernicious, the common opinion seems to be that there is a natural connexion between the minds of children and fairy-stories, of the same order as the connexion between children’s bodies and milk. I think this is an error; at best an error of false sentiment, and one that is therefore most often made by those who, for whatever private reason (such as childlessness), tend to think of children as a special kind of creature, almost a different race, rather than as normal, if immature, members of a particular family, and of the human family at large. (Tolkien, On Fairy Stories)
People have sometime asked if WtL is “All-ages” and I say yes, though I mean as such in the sense in which Tolkien gives above. There’s no gratuitous gore or swearing, but there is danger and death – and without those presented in some form the story simply wouldn’t ring true. Most of the time people assume the story is “all-ages” and there’s been a time or two as I’ve drawn a panel (most recently the one where Thorfin is shown bleeding, apparently dead, in the woods) and wondered if those who passed it on to their kids or students might balk at this.

I am of the mind that the best stories for kids are stories that are well-told, internally consistent, and try to present something in it that is “true” in our world – virtue, beauty, character etc. – while not neglecting the the entertainment, which is the icing.  All that to say, that if you have a child and they are mature enough to understand danger and death in a story, then WtL should be suitable.