Really good watch, probably won't watch again, but can recommend.
More movies need to take a page out of this book. I don't think we need to start with the "dead relative" trope, I'm not a fan of putting people in the fridge, and this makes me feel like I was supposed to feel like I did in "Up!", but it's just not the same. My next biggest problem was looking at a pig and hearing Mila Kunis' voice: for whatever reason it was very distracting.
So what I mean when I say more movies should copy this is the formula it uses. It quickly does some character development and world building for one universe that introduces the other, and the re-establishes the 2nd universe with more succinct character building, a show of adversity / antagonism, some light back story, and a quest to solve a mystery, drip feeding information to the audience.
Honestly, if you're making a movie you can just start at the quest and the audience will catch up, especially if you have re-iterate the situation to other characters. It won't be as charming, but you can fit more movie in, and thus more cool, fun stuff.
I love the "chim-pan-zombies", I think it was an excellent idea. This is one of those "the story if a parallel for real life" sort of things, so of course it's about a young person dealing with their emotions of a traumatic event, but I certainly found myself forgetting about it when they stopped actively reminding me what the movie was actually about.
Great movie pick, good for the whole family, and while I acknowledge the movie isn't for me, there is a good chance it's for you.