The girls are okay, no problem there.
What lowers the rating is mostly that the story is generic : there is a plot, so it's not a bad story but this is the kind of story you have seen already. Perhaps it will become better or reveals its originality in further updates (i'm reviewing up to episode 5) but as for now, it's not special.
The episodes feel very short. Again, not a bad point... IF it's going somewhere and do not say "4 episodes = 1 season = product to sell" because that would be something bad, since episodes last for like 1 hour max.
I found the sex scenes very "normal". Those are not bad, but they are not very appealing either.
I liked the diversity in the girls/roles/bodies a lot.
There are a few choices which seem to matter (as in "choose a route") so it's also not bad on that side.
Edit: the more the plot goes forward, the more random it becomes, losing focus. More girls are added, old girls are put on a bus... visual of the girls change between seasons, etc.