Ah ! I read a lot of negative comments about this anime. So yeah, i was pretty curious.
Everyone has its own opinion and has to not saying to other people, "run, you fools !" because that's a hideous anime for them. We can read their thoughts, got an idea and take its own decision to watch or not.
First of all, you can't call this anime a 100% Hentai. It's really soft, not so explicit (well, for me of course). I don't know if it's because of that beautiful OST but, i'm about to say that's sweet.
Even for this "forbidden" relationship, it's soft. It's not like a big slap in the face and you're totally KO by what you're watching. There is much worse than this one. Of course, that's a little "err... Ooook." feeling but, you're the only one who can judge by yourself.