Eh, I was fine with the ending. It felt like a fitting place to wrap up the movie. What else could they have shown, anyway? Saving Bron was the story's climax, and there weren't any loose ends left to explore afterwards. Not any that I remember, at least. Besides that, all the characters who actually mattered in the movie were already gathered in one place at the end, making the need to see them return to the Great Valley even less important.
Oddly enough, the fleshed-out opening was probably my least favorite part of the movie - at least the scenes with the narration. It went on and on, and all I could do was shout in my head, "Show don't tell! Show don't tell! Show don't tell!" It was too much, even when taking the intended audience's age into account.