When I first played the game, I expected that I would probably hate her route and thus left it for last, despite finding her to have the most attractive looks at first glance. The early catfight turned me off (I just can't find people with overly childish personalities sexually attractive), and also, I had the impression that she would be a tsundere, which I always disliked with frevor , much like overly competitive girl - but that was because they're often spiteful and envious, which Shizune never was. When I actually played her route, she never crossed any "mean-ness lines" or anything, you quickly gort the ideas that she just wants friends and doesn't get how she might be driving people away. Then, of course, I met her father. "He absolutely must not win"... that's often how I feel with my own, who's alot fatter, but also talks in strings of insults... All annoyance I may have had evaporated, and I could understand why she put so much importance into seeminly silly things. But so far, that's the standart fare - "Abrasive girl is abrasive because of sad backstory, yadda yadda, feel sorry for her"
What really surprised me was among the penultimatze chapters, when she talks of her need to do something really relevant (Not just to impress her father - She genuinely cares about doing good.) and road to her life plans, and how she just was so horribly misunderstood and far away from everyone else... I was really surprised, this was really a very different kind of character than I anticipated. The more I reread stuff, the more I grew to appreciate her. Today, I'm very far from disliking her as I thought I would.
It all also comes with the very important message that true love can be hard work and holding on through good and bad times, even when the initial limerence is no longer there. (instead of, for example, cheating because you didn't have much time to meet due to everyday stress and work)