I love this manga, but I hate the ending. The journey to the ending is great, but don't expect it to leave a satisfying taste in your mouth.
The entire manga is about her getting over someone who never liked her and becoming a better person. This childhood friend was only interested in her when she stopped liking him, and when she did he would continuously go after her despite her telling him to stop. He's sympathetic at first, but over time he continues to just string her along while she tries to move on. He's pathetic and spineless.
In the end, she breaks up with somebody who actually cares for and is good for her (which is fine, it happens) and then she GETS WITH THE CHILDHOOD FRIEND WHO WAS AWFUL FOR HER. It goes against completely what the entire story was about, so it's no wonder the ratings on this are so low.