First, let me say this is not a dubbed movie. The Host is mainly in Korean but, since it has U.S. involvement dealing with the monster, some English is spoken.
Second, this is a story of a family bureaucratized (if this isn't a word, it should be) by the Korean gov't which is being bureaucratized by the U.S. The family is made up of an older brother who sleeps alot and has a young child, a drunken university grad who can't find a job ("I helped make this country democratized and it won't give me a job"), the sister who excells in archery but whose flaw is that she's a perfectionist, thus never winning the gold medal because her time-clock runs out (yes, her bow and arrow play a relatively important part in the end), and the hapless father trying to hold his family together.
Third, this is the story of a mutated water creature. This is no movie where you see the shadowy creature throughout and then see it full front at the finale. No, you see the creature full-on from beginning to end. We get to know this creature full well. (Creature courtesy of the folks who brought you King Kong, so there).
Fourth, the creature captures the sleepy brother's young daughter to feed on later. The family unites to rescue the girl.
Fifth, the final battle between the family and the creature is awesome.
This is all I can give you without spoilers. So go see it. It's a family drama, a satiric comedy, and a friggin' good monster movie.
AC