Pretty silly and pretty absurd indeed. Just great (bloody) fun. A dark comedy that does not take itself too serious. That's also something that could be criticized of course and depending on your taste or mood you will just do that. Hopefully though you can enjoy it as much as I and some other people did.
Actually I'm surprised that there hasn't been an US Remake of this (though it seems that there is a South Korean movie/remake). The pace is pretty good, the jokes come pretty quickly, so you don't too much time to think things through. And again, this is not a movie, that is grounded in Reality. It's supposed to be a fun ride, that is there for those who are not easily offended and/or faint hearted!