These are my thoughts on the available translated content so far, which basically consists of the first volume.
Another thing to keep in mind is that the author is Maya Miyazaki.
Many find the rape scene between Lilith's dog familiar and Shin's childhood friend repulsive, and logically it is repulsive to us readers. However, rape, NTR, and cheating are common themes in Maya's work, there's always some form of it in all of his stories.
I tolerate it because his artistic talent is something I enjoy greatly.
Although I did not like the rape scene as a human being, I enjoyed it as someone who wants to see a compelling story. Such a scene conveyed the sense of apathy among the immortals. Lilith did not care that her familiar raped a human and it didn't seem like the familiar was even taught that such matters are detestable. This signifies that humans mean nothing to them.
Not only does it tell you a little something about the immortals, but it strengthens our emotional bonds to the main character and his childhood friend. Most people after seeing and reading that scene will want two things. Just revenge for the innocence lost, and for Shin to enact that revenge. Not only this, but since I'm a spiteful person, I want to see what the familiar did to Shin's childhood friend bite Lilith in the ass. Simple example: Shin refuses to copulate with Lilith because of how disgusted he is in their behavior.
Personally I think the artwork is great, and the story is something I enjoy. There are quite a few stories about immortals and their familiars but something about this one just compels me to keep reading. It's something known yet unique. Not a copy or carbon print to my knowledge and I can't wait for more releases.