Finally after years on my list, I saw this and a bit disappointed - spoilers
This movie was on my watch list for years, and I finally watched it today, and I didn't think it was that great.
I actually did strongly suspect that Mido was his daughter during the scene in which they had sex.
I also just found the character of Woo-jin and his motivations to be off and not convincing. He was too cool for school, kind of like a John Woo anti-hero in 80s HK action movies. There were just some things that were hard to follow, maybe the subtitles did not do a good job - like why did he leave Mido with Park in the hotel/prison while he went looking for Woo-jin?
I don't know, I was expecting this movie to be better. Maybe it is dated? Maybe because I watched Incendies not too long ago, I was on guard for a certain kind of twist.