While this movie definitely references and parodies Korean films, I disagree that a knowledge of Korean cinema is required to enjoy it. While some jokes may go over the average Western viewer's head, the majority are gags in the Mel Brooks style. They transcend cultural boundaries because the humor comes from them being just completely absurd or ridiculous.
It must be said that sometimes this film gets a little lowbrow. One gross-out scene around the one hour mark nearly made me turn around and storm out of the room, but I stuck with it and was quite glad I did- the hilarious chase/shootout later on was well worth it.
I should note that, if this film hasn't got a release in your region yet, you'd better import it, because it's not likely to get one in the near future. The plot, or what passes for it, involves terrorists trying to disrupt the World Cup using liquid explosives disguised as bottled water. That was funny when I saw this film in early August 2006, but a few weeks later authorities thwarted a real-life plot with a similar methodology, so it might be awhile before anyone wants to take a chance on being called insensitive by releasing this. So, if you want to see this movie, check the import stores.