Not sure whether or not we're supposed to feel for Kang. Certainly, great pains have been taken to illustrate his awful childhood and generally bad deal from life's hand.
But, after the first gang rape in which he participates, that just didn't wash with me. Even though his parents detest him, and slap him when he tries to help or be nice.
The opening scene is brief but very gory, as is the closing scene which leads up to it. There's a fair serve of full frontal nudity and sex scenes, including brief but luscious glimpses of Ga Ling (though she's nowhere near old enough to play any teenager's mother !).
There's a moderate amount of drama in the police investigations and the unfolding of the story. Pretty average overall.