I found this to be a really interesting and at times even disturbing VN. It's like a less terrifying, simpler-but-sexier version of Crimson Grey.
The game revolves around trying to manage your crazy yandy GF, either by resisting her advances and trying to help her with her issues, or by getting the shit raped out of you and watching her go insane (which is p hot ngl)
I see a very common complaint about the pussy MC who just keeps refusing to have sex with his super hot nympho gf, but I can't really agree with those. The girl in this game is CRAZY. Not hot crazy, but like there is something legitimately wrong in her brain. Not only that, but she is obviously hiding MANY secrets from you, is trying to dominate your entire life, and it's even possible that she doesn't even love you and is just using you for her own goals.
MC likes this girl, but he wants to figure out what the fuck her problem is before he gets trapped with a pregnancy or something, seems completely reasonable. And if it isn't, then you can go ahead and let her have her way with you, so I don't really get the complaints. He's only as resistant as you make him.
I will agree that the start is kind of abrupt, but I think it's intentional- your GF's insanity hits you like a truck, and sort of is meant to shatter your perception, if it was gradual, I don't think it would be as intensely disturbing.
As far as lewd content goes, there's some basic HS animations, but plenty of well-written and posed stills. The unfortunate split here is that the Love route scenes are a little more vanilla and basic, and not quite as interesting, but the Yandy scenes are... *intense*. Very, very well done. This is definitely a game where you'll need one save for when you want to play the story and one for when you actually want to jerk off.
One thing that worries me is that halfway through the game, it abruptly opens into sandbox mode after like, 2 hours of linear-VN. I really liked the VN, plot-heavy, character stuff, where her personality was shaped by your decisions, and I'm not looking forward to having to grind out a bunch of disconnected events. But it's pretty early so we'll see how that goes.