Kids 8 and older should be delighted with this funny, emotionally involving animated fable about a gangly kid named Hiccup (voice of Jay Baruchel) who becomes a conscientious objector within his tribe of Viking warriors by refusing to kill dragons.
It's loosely based on the books by Cressida Cowell, but the dialogue is more slangy. Try to see it in 3-D, as the sight of Hiccup and his dragon pal in flight would be worth it.
Hiccup's dad (Gerard Butler) is a warrior who feels shame his son lacks killer instinct.
The movie opens with a fiery nighttime dragon attack on the village. Hiccup's clever invention takes down a "Night Fury" dragon, but the boy can't bring himself to kill it. So he sets it free, names it "Toothless," and fixes its tail so it can fly again. He sits on its back, and up they go. Eventually, Hiccup and the other kids teach adults and dragons to coexist.
The bottom line: Parents should be sure kids 8 and older can handle the intense human versus dragon battles. (That's the single reason you might want younger kids to see it in less intense 2-D.) Hiccup and Toothless almost plummet fatally to Earth. The dragons are gargoylish and huge, belching fire, flashing teeth and talons. Their dinosaur-ish "queen" is huge and angry. There are jokes about "undies" and much talk of killing.