It's a lot better than I thought it would be after finishing the common route. At the beginning 3 of the 4 girls were just plain bullies and I had no interest in their routes. However, they all become far more likable later on in the story which redeems some points.
My favourite route was definitely Kaoruko's as she was very loveable the entire game. Mihiro came a surprisingly close second as her improvement and cuteness almost made up for her past behavior. Ashe was OK, she did get nicer but I wasn't as emotionally invested in her route. I did love the foodie aspects of both Ashe and Mihiro's route.
Toa's route was the worst. It did not flow well at all, especially with the whole siblings thing. I couldn't invest in the romance and they didn't make me feel like "this incest route is so believable".