I agree with the comments submitted prior, this manga is too typical, the main character is weak, etc...
But for a formulaic manga, I don't think it's that bad. Yes, you can definitely guess the ending, but since when do (most) shoujo mangas unpredictable? Since it's the quality that almost all manga have, we can't complain much and we can only compare the way the mangaka show us the all-so-predictable plot.
I personally think Kotou Matsu can deliver the story well. There are some scenes which really wrench my heart. This manga does not make me want to scream "MORE!" but it's still quite a page-turner.
Characterization, as mentioned by the others, are probably annoying. My main complaint is not about the main female lead's characterization per se though. It's her character development that I think is lacking. I feel like her development and so-called 'maturity' is too rushed.
Other than the art, what I really need to praise about this manga is actually the side characters. I can say that almost all of the side characters are interesting. So interesting that they could be developed into another story (I heard there's gonna be one. I've only read until 6th chapter, I'll wait for the rest side stories). The main lead's female & male friends are my favorite characters in this manga.