Whom does that leave? People who aren't all that squeamish who place a premium on original presentations of ancient plots, in this case, Revenge. It is a foreign film, but I attributed the weirdness to originality rather than any cultural differences. Finally, I detest implausible movies. While the events in this movie seem highly improbable, I never felt like I was being jerked around by the director.
The plot in brief: After being imprisoned for 15 years without knowing why or by whom, Dae-su is let out just as abruptly. In a typical movie, he would meet a cute girl and the two of them would follow clues to track down the antagonist for the big showdown.
Here, he actually learns the identity of his captor fairly early on, but when he is given the opportunity to deal out his revenge that he's fantasized about for the past 15 years, he realizes he can't do it without learning the truth about why he was imprisoned, and so his captor remains untouched.
For the rest of the movie, Dae-su and the girl he's fallen for, Mi-do, eventually do piece together the truth, with the emphasis on why he was released rather than why he was imprisoned.
A lot of other comments have made reference to Count of Monte Cristo or Fight Club, but the movie I was reminded most of was Se7en, right down to the use of a box.