This game is a masterpiece and a real achievement in storytelling of any medium.
Ignore the negative reviews, but there are some things you should know before buying it. Go in prepared to know that you will feel very sad, anxious, and angry throughout most of the game. There are some lite moments here and there, but this is much darker, more violent, and bleaker than the first one.
I went from hating one character with a white hot passion to liking that character more than just about any other character in the franchise. Very good writing and voice performances. They look, feel, and talk like real people.
This is a very difficult game to write a review about beyond that, because just about anything I say about the story would be a spoiler, but it has incredible moments throughout.