I would say, this is mostly a character-focused game, with a big portion of BDSM, exhibitionism and some sex (by now).
I'm personally not that much into purely punishment for the sake of it, but how the game builds it into the story is well done, The Headmaster is a true perv, but in this crude ingame-logic his silly methods have actually positive results, what makes it hilarious and also quite rewarding. The characters are complex and well created with their own strengths and flaws, people one really starts to care about when playing. And each characters have their own way to progress them, so the game feels never repetitive.
The first lewd scene is actually the hardest one so far for me, less because of the action that is done, but rather because of how it's done. After this, the game gets much, much better for me.
All in all, the game is lots of good erotic BDSM and exhibitionist content, not much sex (yet), but it is definitely much, much more than a punishment-simulator. I really enjoy playing it and only can recommend trying it, even if the punishment aspect might be not your thing.