Great rundown / comparison of the movie/graphic novel, Sev.
I just re-watched the original Old Boy and another movie by the same Actor/Writer combo:I saw the devil.
These are definitely not movies for kids as the violence can be pretty graphic...but i do recommend checking them out if you get a chance. Don't read too far into the links if you want to enjoy the twists.
The actor, Choi Min-sik, is sublime and is breaking into American films in a (marvel unrelated) hero movie starring Scar Jo called Lucy. (directed by Luc Besson)
--Skip the new Old Boy remake by Spike Lee..it starts off ok-ish and starts sucking really fast.