I didn't think there was anything wrong with her personality. She's very reserved, but she does care about people. Look at how she tenderly strokes Yuna's hair when she gets out the Chamber of the Fayth, and when she does the sending at Kilika. And she asks Tidus if he's ok after he chases after Sin. Also, she's had to deal with the love of her life being killed (By Sin, no less) so she's bound to be sorrowful because of that. And her clothes do fully rock. ^_^
