Saying you don't like someone's personality is not criticism its just judgemental and rude. Especially when that person hasn't done anything to be disliked for and yes, it is negative to say that. If you have a problem with who someone is move on and leave them alone. No need to be a jerk. There was no constructive criticism here just plan judgement.
Either way, it's not rude when it's just fictional, people can have there own opinions on the story. It does not affect the author in any way. Plus, I see no cursing of any sort so I don't see why you need to fuss about it., all they said was that they "can't stand the protagonists personality" and that's that. :-:
I can't stand yohan's personality.. Sorry not sorry