This show is amazingly written, beautifully animated, has a solid plot and structure, and shows awesome morals and lessons. Every character is written perfectly, and makes you feel for them. One of the best parts of this show is that it's from everyone's perspective, and shows everyone's hopes and struggles. In addition, the things they are going through are relatable and could possibly help others cope with similar situations.
The art style (and the different types) are beautiful and help to tell the story, and better shape the character's personalities. It may be the classic Pixar art style we all know and love, but it's filled with imagination and love.
I know it's not my business, but in response to people saying that this show isn't for kids, do your research! Not every animated show, or even every Disney thing, is for kids. This explores slightly adult topics, and is really meaningful.
In conclusion, this show is beautiful, and though it may be for people a bit more mature, it is worth watching every second.