Ahh, I see what you mean. The gameplay itself.
I must confess when I review games I review them on two facts, one of it being the art, and the other being playable as hentai games. In this case, the game has really nice art, and it delivers as a hentai game.
As in, you can simply boot it up and get to the meat and potatoes within the first hour and keep playing. To address what you have said, I did play many of the adult RPGs here, both WEGs and Japanese DLsite titles, and a good portion of games this year haven't really caught my eye on this aspect. Often the art is grand, but then the gameplay is tedious and grindy. A game about sex fantasies shouldn't have me talk to every NPC or repeat an action a dozen times for one CG. I also shouldn't have to memorize a complex battle system just so I can get off. I also am a massive JRPG nerd, been playing these since the 90s with games like Phantasy Star, and while having immersive JRPGs is nice, I don't want to commit my brain to strategies when I play a hentai game.
So yeah, that's my grounds on my review. I gave it a 4 star which I feel is very fair for the quality of this product.