Ironically, I happen to be on her route in that game right now.
Eh... I find Amane kind of boring. Only route I've played is Michiru's though, is Amane's any good?
Well...
Spoiler:
Based upon how far I've gotten, I can easily say that she's still plays the role of "slutty big sister". And when you decide to go out with her, she gets even more "needy". In fact, by the time I get to the point where she starts talking about her past (which I had stopped on), I had already seen as many sex scenes as I did playing through both Sachi and Makina's routes combined. Of course, once she revealed her reason for be so doting on Yuuji, my opinion of her changed...slightly. Depending on what happens in the end, it might change back, though.