This game has several bugs (up to and including being booted back to Main Menu out of blue), typos (LOTS of them), the writing is super weak (and I'm not even speaking about the non-existing lore, the writing overall requires suspension of disbelief for every single line).
The renders have bland background (posing is probably fine), it is not clear how the book work (it seems to have passive effects, yet needs mana to activate... uh?), not all girls seems to show on the phone (or it is just not really designed for loading older savegames?). Game seems to have no audio.
Pacing is weird, most stuff happen "because" and even the excuse "because the book" seems to fall short most of time. Oh, and it can be a bit grindy. I won't even mention how time flow sometimes makes no sense (some actions use time and some doesn't, and this rule changes for different characters and stages). Action buttons vanish as you progress, probably intended but breaks the player expectations, therefore falls under bug category.
This game definitely has its charms, of course. The characters aren't totally bland and it caters decently to the fetish; You can see a progression on the girls ─ they change clothes as they get more corrupted, for example. It also avoid almost all pitfalls which could make you want to throw it out the window: It uses Ren'Py (so auto-save even when booted to main menu, quick save, no painfully slow transition, and most of the GUI sorted out by default), and even has some cool things and utilities like being waked up by a girl (no lewds, though?) or a button to quickly return to bedroom.
I honestly have no idea what the dev is focusing on ─ it's not the story, it's not the graphics, it's not the dialogues or character building, not music, not gameplay. I can't cite a single "strong point" or "you should play this game because of X". The best parts seems to be just average.
Granted the game is still in an early stage of development and it probably deserves an average rating, is it not bad (just abuses from suspension of disbelief and has bugs and typos without any particularly redeeming trait), but... as most of issues were present on the demo, "it'll improve later" doesn't seems to apply, therefore, I'll rate it as "Poor".
TL;DR You have no reason to play this one. If you're interested on the genre and already played everything else, this one is fine ─ it probably won't get on your nerves. That's all.
Will keep watching it, though.
Version 0.45