The line at which too intense meets just intense enough in a children's film will vary from viewer to viewer. One picture which I've frequently seen held up in online discussions is Return to Oz, the delightfully dismal yet horribly happy Oz film which surprised 1980s audiences by sticking closer to the trappings of L. Frank Baum's novels than the MGM musical version. The film includes a headless sorceress who holds a collection of living heads within cabinets; the rock-monster Gnome King; the maniacal laughing Wheelies and the Deadly Desert which crumbles people into dust. For me, I found it intense, but to the side of just intense enough. I certainly found the 1939 film much more cheery, but the serious tone of Return to Oz appealed to me, no matter how creepy the Deadly Desert appeared.
My oldest niece is rather fond of Oz and earlier this year I wondered if she should watch Return to Oz, but felt it might be too intense for her. Then I recalled when I first saw the film I was younger than she is now. Yeah, it's probably time to let her see this film.