If this game changed all those repetitive things for permanent stat up it would be better. I agree in the repetitive gameplay, the worst thing was finding ingredients for the all stat up 3. That and the random op enemies that may appear, but well they are easy to escape.
Personally I did a review of this game, but being clear the weak points are:
-Character relationships, the main girls needed more interactions with the MC, we only have the level drain ones without even random events or something outside that.
-Take away all those useless mechanics, add the possibility to develop traits and base the game on items that give you permanent stat up.
-It doesn't make sense that succubi need to kill people and take their souls, it could have been more tame in that aspect, like what happens in a game called desire dungeon, it's kind of similar with you trying to go to the top of the tower, but you had 12 enemies in the tower that remembered if you defeated them, if you ran away, if you had sex with them and if you lose you would get raped and lose a level, but if you won you could have sex with them and earn a new skill or ability.