The reason I give Howl's Moving Castle the highest rating is because it's a war film with the bleak imagery associated, less so maybe than Nausicaä and Mononoke (but more so than Castle In The Sky, which did have a few impressive destruction/war sequences), but associated to that there is also the ugly-surrealistic magic imagery of later Miyazaki film (a tendency that starts in Mononoke but really explodes from Spirited Away onward), and in my mind the association of the two could be rather impressive, but maybe I don't know children really well, and I can't really tell from my own experiences either, I tend to be more affected *now* by movies that as a young kid I watched without batting an eye; The Dark Crystal, The Secret of NIMH, The Land Before Time, watching those at like 5 and no problem, not scared.
(But then I watched Grave of the Fireflies at 15 and THAT severely punched me)
(and I might have been slightly traumatised when I accidentally watched a good deal of Fritz the Cat at the age of maybe
