I played this on Steam with the game being on season and all... and I enjoyed it a lot!
The dialogue actually entertained me and kept me in focus for the most part, the characters were fun and cute, and I liked the final exam where you get to solve the problems through multiple means (insubstantiate ftw).
Tbh, it was the unique LIs that got me to download the game (you don't get to romance a poltergeist or a frankenstein monster that often...), and well, they're also the ones who made the game for me. I loved Zero to bits. I smile every time he goes on screen; I wish we got to learn more about him (unless I missed it). I'm just curious was his grudge was.
As for the MC... I know a lot didn't like them, but I gave em' a pass cause given the setting of the story, I wouldn't be surprised to see a kooky character like them. Maybe they would have been more likeable if they showed more vulnerability? Like when they were worrying about losing Zero or when they were comforting Damion? They were just too peppy 99% of the time, and it would have been nice to see more sides to them.