[Spoiler] This game has a lot of bad reviews based on the ending. I think people missed the reference; Ellie was asked in the first game what her worst fear was. She said "ending up alone" and "everyone [she] has cared about has either died or left her; this is exactly what happened. Her revenge quest drove everyone she cared about away from her. This game is amazing because it portrays humanity and its cycles of violence. She wanted to kill Abby because she killed Joel who was a father figure to Ellie.
Although its sad, Joel killed Abby's father. So they both had a reason to hate each other. But by Ellie sparing Abby she ended the cycle. Who is to say that if she killed Abby Lev would kill Ellie, then Dina would kill Lev? This game is so realistic with it's ending and I believe deserves a better rating.