I will disclaim that I am a bit biased as the author is a good friend of mine, and that there's only two versions so it's hard to judge overall long-term writing, but I can give my honest thoughts on this VN as it is now.
The writing is outstanding. I've read a lot of Western VNs; some of which have objectively bad writing but I stick through because of the tags or visuals or character design, or some combination thereof. I've also read VNs with very good writing where I'm not a huge fan of the mood or tags or whatever but stick with it because the writing is damn good. All this to say, I've seen a lot of Western VN writing, and this one is absolutely well written. Although almost all the writing is in prose, it sometimes feels almost like poetry. Not in the mechanical structure (rhyme, meter, etc.), but in the thoughts and feelings being expressed, and the way in which they are conveyed.
The characters are in-general well written. None of them conform solidly to tropes, or feel like vehicles to move the plot along. They all have personalities that seem to be revealed naturally. I don't currently find Kei (the protagonist) to be super likable. I've talked to the author about this, and I understand why he's like this at the moment and why he's not present, but I think his character is, at the moment, somewhat of a detriment. I do really hope he becomes more likable, as we're going to be spending a lot more time with him. The other characters, the girls, I do very much like. Senri manages to both be somewhat of a comic relief, while also having her own thoughts, wants, and logic besides "haha funny thirsty bi girl". Miu is probably the second most interesting character to me. She's introduced in the early events as being a little ditsy, but in v2 she shows more of her character. It's hard to pin down who she is, but her personality manages to be intriguing without feeling unnatural.
The visual design is another great aspect of this VN. Again, I've read many of different levels of quality, even many using this specific engine (KK), and this one ranks very highly. Gasha spent something like a year toying around with the renderer and refining it before starting work on the VN itself, and he puts a lot of effort into the visual design. But you can see much of that from screenshots so I will not write several thousand words in their place.
All in all, this novel is in its early stages, but I really like what we have so far. I would recommend it, with the caveat that this is a VN first and adult second, so if you want something that has more emphasis on the pornographic elements I'd recommend something like Once in a Lifetime (not a diss on that game, I genuinely love it, but it's much heavier on the fan service). This also isn't for you if you hate the mere thought of lesbians existing, which apparently some folks in these comments do. But if you want a well-written slice-of-life romance story with compelling characters and beautiful visuals, I advise you to check it out.
