People are mad because (minor spoilers) the main character from the last game, Joel, is brutally killed off at the start, and then you play as his killer in the latter half to understand why she would do something that awful. Players can't get over this and it taints their view of the story.
This game's objectively the masterpiece that all the critics say, but the players rage, lack of self honesty and desperate need for vengeance ruins it- Just as it does for the main characters. It's pretty brilliant, actually. And just like the main characters, the audience is slowly starting to come around and realize how foolish they've been- The metacritic score has risen from 2 to 4 in only a few days, and it'll keep going up.
Personally? I had no problem with it. I'm thrilled they killed Joel. The guy shot up a hospital and ruined humanity's only shot at undoing the apocalypse, leading to millions more deaths. (This is indisputable if you heard the voice logs in the hospital).
I just wish Joel's death had been a player controlled moment. It's not every day you get to kill Hitler. 9/10, miserable but amazing.