I remember watching a special or reading the info somewhere. The movie Yellow Submarine with the Beatles had animation that was new way back then. Where they made the buildings look three dimensional to give it all depth, that style was not used till their movie. Now I think it would be very hard for animators to find new ways to animate since so many have already been used up.
that was a cool, and very fresh idea behind animation,
combo 3D and 2D, also, had a little bit of "Incredibles" feel to it......maybe the music.