I totally lost it at Olaf's song about summer. XD I'm glad he didn't end up melting in the end, though, since the movie was basically hinting that the whole time. And I'm glad that the older sister didn't turn villainous at all. She's too cute and innocent to be a villain.
I feel quite bad for her, especially regarding how her parents went about treating her powers the wrong way and how it only made things worse, despite them having the best of intentions.