I can`t say much about this manga because I`m not that familiar with the romance genre, I only read a few others like GE: Good Ending and some others I forgot the name. What I can say is that the characters are interesting because they do have flaws but aren't unlikable, the plot is kind of original, but these days you'll always be able to find something similar, there are a few Deus Ex moment in the end because said character is basically useless for work since she ditched school.
Now, comparing this manga with similar ones in the same genre category I would say that this manga is missing that "the story is so great that it can make you feel butterflies in your bely", like I felt with GE, and similar - but different - with tragedies like Graveyard of the Fireflies or any great drama out there. But I'd say that the reason for not having that is because the mangá is so short, 21 chapter is barely close enough for a good character development, imagine making your plot so deep it makes you really care about them.
