Honestly, the story itself was nasty and upsetting. The body horror was great, and that's the reason I read the manga, but I wouldn't really recommend it to anyone else since the incest and emotional manipulation within it was highly disturbing.
In a way, the story did its job; I finished reading it like maybe 10 minutes ago, and I'm still disgusted and upset, and I'll probably continue feeling uneasy for a while. It gave me the feeling of the smell of old books in a used book store, if that makes sense? It wasn't frightening in like a monster sort of way, but more in
a way like "this is something that could happen in real life", and that's probably the worst part.
Basically, I hated the incest and abuse aspect of the manga, but I suppose that was a really important part of it as well since it made me extremely uncomfortable, which is a form of horror, I guess. I liked the body horror though, and for me that was kind of the reward for reading it because it was not very enjoyable.