@Rumpelstiltskin said:

Pretty decent flick. Quite original and gory, right up my alley.

Law Abiding Citizen was partially similar, though not as much gore, but a bit similar topic.

Great film. I love South Korean cinema and their thrillers are so good! Here is a list of some of my favorites:

Memories of Murder 2003

The Chaser 2008

The Man from Nowhere 2010

and the Vengeance Trilogy is a must!

Sympathy for Mr. Vengeance 2002

Oldboy 2003

Sympathy for Lady Vengeance 2005