The story line resembles "The Neverending Story". In this case, a monster is consuming the world into a "Nix". As with a black hole, the world is sucked away bit by bit. While this is happening, a boy is wandering around looking for his vanished grandmother, and encounters lots of weird creatures along the way. They tell him about the monster, and why everything is vanishing into oblivion. Will he and the creatures be able to stop the inevitable end of the world? And if they do, will the remains be worth it?
The animation is really something else. The atmosphere reminds of a Tim Burton film. The creatures are really weird, and the story is a bit erratic at times. The songs are a bit weird as well. However, in al its weirdness, the animation is very beautifully done.
If you have seen it all and are looking for something completely different, this is your film.
If you just want a normal enjoyable animation with clear characters, simple entertainment and a more or less recognizable storyline, look further.
As I am of the second category, I did not enjoy the film very much. But I can see why it was sent as an Oscar entry: film critics will probably love it.