A Way Better Ending (Spoilers)
First of all, when Bok-Nam gone mad with a sickle on her hand, the movie suddenly started to a earn symbolic meaning for me. She is the working class, being used, exploited and raped by her capitalist husband (and his brother). Hae-Won is the conformist, educated intellectual, upper class, selfish as hell who gives a *beep* about her. And the island is symbolizing the modern world. Not just rural village at sea (and of course it is symbolizing the women, great scene btw, but I'll pass the obvious feminism issue here)
Well, I have no problem with Bok-Nam dying at the end. After all, she lost clearly the only and most precious thing of her life: Her daughter, whom she learned the day she died, that she loves her mother more than his father. The other thing important in her life was Hae-Won's friendship, which turned out to be worst. She betrayed her each and every time (that was even OK, but when her daughter murdered too!) Plus, what is she gonna do in the mainland? with murders on her hands, lost daughter and friend. Practically no reason to live.
Also at the fight scene where the daughter bites her molester father's knee... Well, having her bite his dick would be a great irony, *beep*
At the final scene, they should both have been killed each other. She should sledge-hammer down Hae-Won's head and blow her brains out all over the ceiling wall! Too violent? Go to hell! SHE WAS THE ONLY ONE WITH BRAINS ON THE ISLAND AND SHE REFUSED TO USE IT FOR ANYONE'S SAKE. Including the little girl! She was just gonna leave the island, like nothing happened. The old auntie convinced her so. Always sleeping like a pig at her house. She should also been buried in a pile of *beep* like the husband. OK OK I have gone too far. The thing is, she deserves to die. Otherwise, it leaves a big dissatisfaction. Bok-Nam hammered the police officers' groins and should hammer down Hae-Won'a brains. Clear reason for this: Men misuse their dick, women misuse their brains in this revenge movie. Hammer'em!
So, the final shot: Bok-Nam hammers down Hae-Won's brains out (from side, not on the face). Cuddles her and while they are both dying, we see the police open and read the letters she sent her, simultaneously mashed up.
Not a cheap "They did it!" redemption scene at the police station. C'MON!
http://www.imdb.com/mymovies/list?l=5844404