The main issue is that the story/gameplay loop and the H-loop are basically separate. The H progresses by moving across areas, but you have no reason to do that in the regular gameplay loop since you never need to leave the dungeon. And so you either rush the story or farm the H-loop by hopping across areas, but that's even less satisfying than just watching the H-scenes since there are loading screens and it removes the feeling of forced corruption.
It's not a 1* because some of its parts are good. I like the MC's design and appreciate the basic line-art, though some of the H-scenes lean into it too heavily and feel flat. Some of the anatomy is weird too. The dialogue is decent - a few parts are unnatural, probably lost in translation. The plot is slightly better than standard, and the gameplay is overly basic.
It's not a 1* because some of its parts are good. I like the MC's design and appreciate the basic line-art, though some of the H-scenes lean into it too heavily and feel flat. Some of the anatomy is weird too. The dialogue is decent - a few parts are unnatural, probably lost in translation. The plot is slightly better than standard, and the gameplay is overly basic.