While she's not hideous, it's quite unusual for any manga to have a character that doesn't have the "perfect anime face" in such a major role. I mean, even characters that are said to be plain usually has the "anime face", and you can't really tell that they are plain from the way they are drawn, only by how other characters talk about them and react to them. At least here you can see that her facial features significantly deviate from the other characters. Which is quite novel and interesting.