Firstly, I would like to say that the art is amazing and the animations aren't half bad either, but the facial expressions could really use some work...
Now as for the story and the sexy times, I'd say they are pretty bad. The story is pretty non-sensical, seems very random and a lot of the stuff that happens makes no sense, which in turn makes the sexy times not that sexy. Especially for Asami, that escalated way too fast and Natsume just doesn't make sense as a character.
All in all, it's an okay game, I liked it much more on update 3.0 where i last played it, I have hopes that things will come together though.
Edit: V0.6.91 Okay I have finished the revamped game now. As everyone else has already said the art and animations are amazing, top-notch. The story is okay, it has a lot of cliches, and they're done well.
I am changing to 4/5 now since the only thing missing now, and it is a big thing, is me feeling connected to the characters. We need much more dialogue I'd say, even though the scenes are objectives sexy they don't do it for me. Keep up the good work I believe it's going to be a great game.