I thought this series had potential when it first began. I'm a big fan of heavy and serious themes in manga, but as it went on I think I found out why people are giving it such a low score. I think the premise is great, actually. It's a very real issue in society and I do have to say that I can see why the MC decided not to tell her friend about it (sexism of society, etc) but then it gets a bit convoluted because there's too much shit going on. Granted, the manga's trying to show the perspectives of all the parties involved, and how they affect the people around them. But the thing is, there's a lack of direction which is probably where the "she's making stupid decisions" thing comes from. The student/teacher romance isn't really helping its case.
I still think it's pretty daring for doing this! Despite what I just said, the manga has more pros than cons. Give it a read if you're interested in serious, and psychological topics. Thankfully, it doesn't portray rape in a sexualized manner, and the psychological aspects have weight to them.