For version 0.5.5
It's one of those games by an artist, and written like a book.
This game is getting rave-reviews, I can clearly see the effort that's been put into it, and it's not making any mistakes that a bunch of other games in this genre aren't also making, on account of also being made by people who haven't made games before.
...but if you don't call out the misses, how are we ever going to get the greatest hits?
So, credit first: This game has a really unique artstyle that helps it standout form the crowd, and gives it it's own "character". There is not only an entire comic's worth of art and even short scenes getting multiple "panels" to let the story breathe a bit. Big boobs and butts to the point of comedy, yes, but not handled distastefully. (edit: Nvm, it does go there eventually) Many scenes also have animations.
The plot is pretty derivative from similar stories, but the game is clearly going for the mass-appeal, so that isn't a huge issue. Your teenage MC is bland, and gets a huge dick and the ability to shoot ropes. Also "mind control", of the variety that lets you set up scenes without further setup. Very simple stuff.
The gameplay is what every RPGM-VN has, which is walking at things and pressing Z. Some games have managed to squeeze interesting gameplay out of this, but Demon Deals is not one of those games. There is a lot of blatant padding, little tasks that only exist to lengthen the game by making the player do chores of walking around pressing Z for no reason. As high as the bar is for the art, it sits in the Mariana Trench for the gameplay.
The cardinal sin of RPGM-games is also here, which is having large open areas with nothing in them. Hopefully future-versions will do the sensible thing and just section off areas with no gameplay-purpose until they get content. The game's events are mostly on-rails, and an open-world style would require the game to change the structure of the game to match the intented experience for the player.
I am also highly critical that there is no gameplay at all, aside from the resource-management of spending money. A lot of VN's have managed to make resource-based VN-gameplay interesting and viable, and the magic-system would have been a perfectly reasonable fit for having some sort of simple, "gamified" level for gaining and spending abilities to progress, or just to have some control over which order you see scenes in. But the game isn't doing that so we just have the story, with the magic primarily as a visual element /theme.
One good way to point out bad design is the MC's house, your main hub. The room you will visit most will be your room, where your bed is, and to access your bed, you need to walk to the other end of the room from the front-door. Between the bedroom and the living room, there is also a door, which forces a half-second pause of "immersion" to pass through. When you get outside the door, you have another half-second to load the outside map, and you have to turn down the "stairs" and take a nother half-second to walk down before you're finally in the overworld. and can start moving torwards some place.
What's the problem? There are two extra pauses to start and stop, each time you want to move from your primary location. Yes, this is how real houses work, but this is a videogame. The convinience to leave the bed and explore the world should be valued way above realism and immersion, in a game with this kind of lifesim-cycle that starts from the same place every day. Some games don't even bother including the process of waking up and moving to the door, and just let you pick your destination for the day from a menu, because why would you want to do that walk every "day"? This is a really tiny thing, but the game, and games like it, are characterized by these kinds of design-decisions where the focus is always on what the developer can accomplish, or what they have time to implement, and not on how the player will interact with the game to have Fun. The flipside of this are rooms with nothing in them, or a plot that gets pushed forward by a character just giving the player the "answer" in an empty room near the end of the game. And it's also why this game has it's locations spread out randomly from the home-apartment.
So yeah, rant over. I'm not going after the writing. I don't usually like pure VNs, even if this one is inoffensive. Game-design is it's own skillset, and it's hard.