I think she has a great voice but I don't understand all the hype surrounding Frozen. It was cute. It wasn't anything spectacular IMO.
The thing about
Frozen is that for Disney, it is a new take on the idea of true love and self-respect, and it plays very strongly to the grrl-power movement.
Mulan went in this direction, but had a traditional romantic ending.
Brave was another step, but stopped short of putting the heroine entirely in charge of her own life, let alone a country.
Let it Go is an anthem. It was designed to be an anthem, and many people feel that it mirrors how they wish they could live but are afraid to. They are finding that the song reflects the current turn against societal conformity. It promotes the idea of embracing your strengths even if others do not understand them and might even shun you for displaying them, and it does it in a musically pleasing way. (However, it is a bear to sing. My DD6 is enthralled with it, and we've all been living in off-key hell while she practices it incessantly. She's improving, but nowhere near fast enough!)
Frozen is a good Disney film, and will be a classic. It's not at the level of the
Lion King (hard to top
Hamlet), but it is ideally placed for release at this moment in time, with the way that societal tides are turning these days. Blood is thicker than water, and in
Frozen, it's thicker than marital romance as well. (It also helps that the leads are very pretty, and the dress designs are lovely and lend themselves to real-life construction.)