Personally not a fan of sad endings, bittersweet endings like the cyberpunk anime are nice, but I dislike sad endings.
But according to the author, this one has some autobiographical elements to it, so it's more of a passion piece than a purely horny one I'd say. It is an early work of theirs and they haven't done much like this (except for the Seed of Destruction wife) She was originally meant to be a more femdom bitch character that starts weak but gets stronger from stealing the lifeforce of the main character. She was even meant to be wheelchair bound, but apparently the artist decided against that cus it'd make it hard to do lewd scenes.
Honestly I think it's nice, I'd give it a slightly lower rating because of the sad ending, but I'd up it again anyways cus it's an artist's passion piece.
"This is good, isn't it?" I really enjoyed this story, it has so much effort put into it but... god, the ending, that is sad. I didn't cry, but this is sad.