This is a monster horror movie that really tries, to the point where they don’t give a clear view of the creature in the previews, presumably not to ruin the initial shock moment for the viewer. It is in Korean with English subtitles, with a few bursts of English with Korean subtitles when the speaker is American.
The movie focuses on one family’s ongoing battle: not merely against the monster but also struggling against the authorities who want to capture them, suspecting they have been infected with a virus by coming in contact with the creature.
The dialogue is pretty ordinary. I seem to recall a few unintentionally funny moments, though I cannot say for sure that it wasn’t due to the translation. I don’t intend to be hyper critical here: I sort of let the movie wash over me to get to the end, and you may or may not need to do the same.
I found I was a little confused as to the final fate of one of the family members at the end. Perhaps I was inattentive and it would have been cleared up if I backed it up and watched again, but unfortunately I wasn’t quite inversted in the movie enough to do that. I put in my time and that was sufficient unto the day.

These sites all missed the point. It's farce, it's funny. I actually liked the creature! He's kinda gruesomely-cute! Don't expect drama. It's all tongue-in-cheek, reminiscent of the old Godzilla creature films.