I'd have to say this is one of Pixar's lesser efforts. It just seemed like they weren't sure what to do at times and ripped off parts from other popular animated movies before veering back to Pixar quality story telling and that made it feel tonally uneven; which is unusual for Pixar.
[Show spoiler]A lot of that IMO was due to the puberty aspect of the storyline. You could tell Pixar was pushing its (and Disney's) boundaries when it came to telling that part of the story, but at the same time felt like they either didn't know how to do it properly or someone forced them to downplay certain aspects of it causing the better Pixar storytelling to be sacrificed as a result.