It's ending is sort of bittersweet, and it's a pretty sad and definitely not very lighthearted like other Disney movies. Quite dark, in fact. That said, I think it's fine for 4 year old, because it's good for kids to get exposed to sadness and the real world at a young age, instead of Hannah Montana's "ANYONE CAN BE A STAR!" thing, which is really bad because it gives kids unrealistic expectancies, but that's OT.