After watching this again, I came to like La Luna much, much more as a story about a boy learning to find his own way and develop his own identity while his father and his grandfather both try to impose their respective characters upon him. It's much less fluffy than I gave it credit for, and it of course remains very, very beautiful.
For the film itself-- I still think it works. But it is very much under-served in a few areas. I really wanted Merida and Elinor to have more time spent bonding with one another in the woods, particularly along the lines of the river scene, which is quite lovely. But I think that would have meant adding onto the story, since there's very little here that can actually be removed easily. Nothing wrong with additional footage, I say-- this is a mercurial movie. It just breezes by. And while that's kind of nice for its own reasons, I think it could have done with some drawing-out. Coming out of the theater, I wanted more time with mom and daughter, and I wanted to see a little bit more of how their adventure changed them in the postscript.
Also, re: Merida not really using her bow. She uses it plenty-- salmon fishing!-- but when it comes to the climax, her bow is useless. She's already put arrows into Mordu, and she knows that she just made him mad. Besides, I don't think that the bow defines her; it's only one symbol among many of her defiance of her role as a princess.