Yeah, this book is a lot to process, but not in a bad way, necessarily. It's more literary with a little bit of magical realism thrown in than typical fantasy. It's also not an easy read, in multiple ways.
My first warning to people is do not try this book unless you are willing to read graphic depictions of child abuse. It can be really rough. I think we also tend to think about child abusers as people who are pure evil, hate their kids, and deserve to be locked away forever, and while I'm sure a lot of them fit that description, that's very much not the depiction this book is going for. The abuser is a deeply human and tragic figure here. It's clear that Joe loves Simon a lot (and Simon loves Joe back), even as Joe brutally abuses Simon. And that's hard to swallow, and it's also hard to deal with watching other characters not intervene sooner.
Kerewin (the artist) is an interesting character. She's pretty clearly an author self insert in many ways and can also be a bit Mary Sue-ish/which fulfillment-y at times (she's rich, she's skilled at all sorts of random things), but this didn't bother me because the way she interacts with people and the world around her (which is where the conflict in the book comes from) felt like it was pretty realistic. She struggles with a tendency to self isolate in a lot of ways, but I did appreciate how when she does connect with people, she does it in her unique way. She's also aro ace (and so is the author) (although she uses the term "neuter" for it because the term aro ace isn't something the author knew about at the time, but "neuter" also seems to encompass her being childfree and gender nonconforming). I appreciated the depiction of being a-spec but not really being able to have an official word for it or a community around it, I think it was a good depiction for that experience.
This book is deeply rooted in New Zealand (including its Maori history). This goes beyond just the setting of the book to the style of the book. Maori words and phrases are used relatively frequently, and even English words are spelled in a nonstandard way to reflect accents (and also Kerewin's perspective). It's more stylistically challenging than that, Kerewin in particular has a large vocabulary and isn't afraid to use it, and the book will sometimes change pretty randomly from narration to showing the inner thoughts of Kerewin, Simon, or Joe, which can be a little tricky to keep track of. But overall, I appreciated the unique style, even if it was challenging at times.