There were loads of kids at my screening yesterday, and none of them screamed, cried, or had to leave because of the violence. That is obviously anecdotal and doesn't necessarily mean it's not "too" violent, but it seemed fine to me. Aslan jumps Jadis and eats her in The Lion, The Witch, and The Wardrobe, and there are some pretty graphic scenes in that kids' movie too. Ultimately, it's all subjective; every adult should know themselves and the children they take to the film and know whether they can handle it or not.