The story and look is a bit more traditional Disney than it is Pixar. Which immediately is not the greatest impression I could get. But some details seem promising, for example lookit the screenshot. I like that the her hair looks more hand-drawn than it looks rendered. It adds a bit of the abstraction I'm missing in the trailer otherwise.
Ah yes, lack of abstraction, that's what felt weak to me. And of course, I'm not crazy about pre-industrial stories or fantasy in general, paradoxically most of it seems to lack the very imagination which the genre by definition allows so much of.
And there's rumors that the next-next Pixar movie will be quite abstract, taking place in a girl's mind with personified emotions, sounds interesting.
I have read that when Pixar was little and unproven, they had to resist a lot of pressure from Disney to make Toy Story a musical. For one, I'm happy they did!
Not that I dislike Disney, I usually enjoy their films. For example Hercules and The Emperor's New Grove are very funny (and lovably abstract, especially the latter), good, and seminal.
Alex mentioned ParaNorman. That looks like fun. And the light in it is beautiful, see for example the short clips neat the beginning of the trailer, of the sunrise-lit street and the hero seen through a window. It seems to be a stop-motion movie, I wonder how they make such beautiful lighting.