My daughter is eight, and we read it together last year. Honestly, I worried the Christian allegory stuff might be too heavy-handed or boring for her, but she didn't pick up on that layer at all. What she latched onto was the talking beavers and the Turkish Delight. She got so mad at Edmund for betraying his siblings over candy, it sparked a whole conversation about trust and bribery that felt way more organic than any lecture I could give. The battle scenes are exciting without being graphically violent, and Aslan's sacrifice, while intense, is handled with a kind of solemn magic that she found moving, not frightening. We've since read the whole series, but 'The Lion, the Witch and the Wardrobe' remains her favorite entry point. It's got that perfect balance of a clear, propulsive adventure and moments of genuine wonder that just work for that age group. The pacing is brisk enough to hold attention, and the idea of finding a whole world in a piece of furniture is eternally compelling. It absolutely holds up.
Sometimes I think adults overcomplicate it by focusing solely on the symbolism. For a kid, it's primarily a cracking good yarn about four ordinary children who get to be heroes in a snowy land where it's always winter and never Christmas. That premise alone is solid gold.