A defense to some points thrown around.
Story:
Hating a character doesn't make a story bad. having an unlikable main character can be used in a way that makes a great narrative.
Some say the main character is not developed but has a 45 page list of reasons why they hate him. That being said, the characters are still shit.
A story can be about something "bad" like murder and still be good. Some people say the story is shit because they're disgusted by prostitution and sex work. Even if your morals say it's bad, a story can talk about those themes and be good. Still, that being said, The story is shit. The main character is a knight in shining armor that has come to save the poor girl from sex work. Its shit, and done in a shit way.
Art:
This guy is very good at drawing, and I believe his assistants are very skilled individuals. Still, art is not just being skilled at drawing. The drawings don't convey any feelings and the dialogue could be just plain text in a novel. The drawings are just the background where these words are floating. It doesn't add anything to the story.
Enjoyment:
One day I finished a great manga and thought to myself "Happiness needs sadness, so maybe I need to read bad manga so I can really appreciate good manga."
In a fit of rage combined with self hatred and destructive impulses, Ive binged 100 chapters of rental girlfriend.
those were painful hours to bear, but I think I have a new appreciation for good manga
Overall:
It feels like the author has nothing to say.
He touches on some themes like sex work, aspirations, ambitions, romantic love. But doesn't have anything to say or comment. It makes sense if we think the person who wrote this is a regular otaku guy that doesn't know anything about sex work, romance, relationships and everything else in the manga.