You're allowed to be critical.  Constructive criticism is always good.  Keep in mind though, that like most Harry Potter stories, this is from Harry's perspective, and as a teenager he's not that introspective about how his own behavior in the past may have caused Snape's attitude towards him.  To Harry, all he sees as a teenager is another adult being unfair to him.  This is a common thread of thought for most teenagers.  They often feel oppressed by their parents or guardians and unjustly punished.  I never said that Snape wasn't right in some ways, but the story is mostly from Harry's perspective, so the reader is seeing through his eyes, feeling what he feels, thinking what he thinks.  As Harry grows and matures it's his job to be more introspective.  If I never started Harry out as somewhat in the wrong in the way he thinks, then he would end up being a flat character with no room to grow.  Snape has already shown him to be a round character, as he grows and realizes he's been wrong in some ways and admits that to himself and others.  He is still growing.  So is Harry.

Thank you for your review.