I'm not a huge fan of Kirino, but she does seem to be more of a hardcore tsuntsun in the anime version. I mean, think of how deredere she was in 8.04 (of the manga):
True, she is an unappreciative little brat, but it's also very clear that she does love her onii-chan in her own way. She's just too used to being ignored by him and being a bint to him that she doesn't know how to properly express herself.
I just hope that her attitude is addressed some day (with flashbacks to her childhood with Kyosuke) and she learns to let go and show her dense brother how much she really cares. Because as long as HE understands how she feels - whenever that happens - who cares what we think about HER personality, nay?