I really like this article: 7 Moments That Made 'Frozen' the Most Progressive Disney Movie Ever - PolicyMic
Now you want to read it with the pretty pictures, but here's a summary for people can't do that right now:
1. Portrays parental abuse in a way that's relatable to children.
2. Elsa's self-empowerment.
3. Anna's entire personality.
4. Kristoff isn't intimidated by or bumbling in comparison to the strong female leads.
5. Oaken the shopkeep has kids... and a husband.
6. Rather than being a princess who marry's a prince, Elsa is a princess who becomes queen... and her people love her.
7. "You can't marry someone you just met."
They're all super great... If I had to pick a favorite (and I don't, but I will) I think it would be number four. There's been a trend in empowering women by degrading men, but all three leading roles manage to be strong characters without tearing anyone down, and I found it really refreshing.