Lee Shin-Ae is this movie.
Not only does Jeon Do-Yeon carry the entire movie, but her character becomes the movie.
Like its protagonist, the film initially parades around town in a veneer of normality and happiness (i.e. blandness and disinterest), acting richer than she really is (through nifty camerawork and showy side performances), but hiding a plethora of internal problems that explodes in the third act (in the form of juvenile pranks and hysterics) and ultimately leads to her being unable to deliver the payoff (eagerly promised by the numerous thematic setups).
And then, further emphasizing its central theme of denial and repression, the film runs about 45 minutes too long on the fumes of its own self-importance.
Secret Sunshine: 4/10