Although quite a good adaptation in many spots, I think that the parts of the original text that were changed or left out for (I assume) brevity were actually quite important, and the story loses something by not having them in there. In particular, the Emperor's final dialogue with the nightingale and its final words to him, as well as the story of the mechanical bird (which in the story is a lot more impressive and has a much bigger impact than the one in this film).

I think that the creators maybe didn't feel that those things were important, with which I have to disagree.