While the full game isn't out yet and I'm too lazy to look up the leaked gameplay parts, the essentials are:

Joel gets killed early in the game
Halfway through the game you start playing as Joel's killer Abby instead of Ellie
Ellie is the final boss of the game, unknown whether she dies or not after
There's a very tame foreplay scene that gets interrupted, which apparently was noteworthy enough to get a mention here