*[SPOILERS]*
People with either love or hate this game, showing just how decisive it is. But if you want to enjoy the game, my greatest advice is to go into it without expectations.
Those who rate the game poorly because they killed a beloved character, or because Ellie didn't kill Abby at the end of the game did not understand the game's intent. It was reiterated time and time again, "If I ever were to lose you, I'd surely lose myself". Ellie loses herself in a rage to avenge Joel. But by choosing not to kill Abby, she saves the ounce of herself that she has left. Abby is on a similar path to Ellie at the beginning of the game, and although she succeeded in avenging her dad by killing Joel, it didn't bring her peace. Her nightmares only subsided after helping Yara and Lev which is unarguably what her dad would have wanted. Ellie's failure to realise what Joel would have wanted resulted in her living out her worst fear, "ending up alone".
As such, the story is not as simple as revenge but rather it's about grief and perspective. That's not to say that Naughty Dog executed it flawlessly, with the game's biggest fault being its pacing. As you reach the climax of Seattle day 3, the game sends you back to play day 1 to play as Abby. It's jarring and completely understandable as to why a player would put their controller down and return to the game. Persevering pays off because the truth is, the story is heart-wrenchingly beautiful. It has all the right material to be great but its potential is failed by its order.