Let me open with this.
That should open this up nicely.
If you've seen 2010's Tangled, you have a nice idea of what to expect, both musically and in terms of humour (if you haven't seen it yet, you REALLY need to).
Frozen almost takes inspiration from Tangled and takes it up a few steps. Granted, the composers are both very different (Christophe Beck for Frozen, Alan Menkin for Tangled), and in Frozen the performers are primarily experienced actors/singers from Broadway/stage performances. This makes the music so much more larger than life than what we're used to. Then again, everything in Frozen is, to a great extent much bigger, both vocally and the elaborate, beautifully created environments.
Loosely based on Hans Christian Andersen's 'The Snow Queen', Frozen centres around a young princess, Anna, and her older sister Elsa who was born with mystical 'cryokenisis' powers (yeah, that's a thing, Wikipedia says so.) which enable her to manipulate and generate ice/frost/snow at her will.
The opening minutes of the film focuses more on the older sibling, Elsa (played by Broadway singer Idina Menzel) and her struggles with trying to protect those around her and controlling her powers. It's after this the film turns its focus to Anna (Kristen Bell) and her journey.
Though Frozen is a principally a Family film, make no mistake; this film is one for EVERYONE. I couldn't count how many times I laughed out loud at this. It's been a while since I've laughed so much at a film, especially a Disney flick. Most definitely (and oddly, surprisingly) one of the funniest films of 2013. Specifically look out for the hilarious exchanges between Kristoff and his Reindeer, Sven. Some of the biggest laughs came from these scenes.
If there's one film you need to watch this Christmas, it's Frozen. Funny, heartwarming, charming, though the obligatory cheesiness may get on older viewers' nerves, it's expected of a film in this category.