Everything I've seen of her shows she is extremely cold.
Here's most of the reason why I don't like her, though. Interview below. The interviewer asks Hemsworth what the relationship is like with his stunt double. He gives a simple response, then Larson butts in, and, 1) acts "fake incredulous" that Hemsworth doesn't do his own stunts, and 2) feels like she needs to talk about how she did her own stunts, as if at some point in the interview someone said she didn't, or that it's bad if she didn't. Hemsworth VERY OBVIOUSLY JOKINGLY calls her Tom Cruise (which why in the hell would you be offended by that? because he's a man?). Her response is one of both overreaction and nonsense. I would liken it to someone throwing their Whopper back at the cook because they didn't put onions on it.
Most of this interview is cringeworthy because of her. She is overly-sensitive to the world around her, always trying to prove that everyone is against her, specifically because she's a woman. She creates drama where there isn't drama. I just simply don't like that kind of person. Watch the interview. MOST of her facial reactions are of a person that would not be fun to talk to in real life. Question at 2:10. "Moment" at 2:33.