This monster movie breaks convention early on by showing the creature in broad daylight
Wikipedia says 'The Host' was inspired by a local article about a deformed fish with an S-shaped spine caught in the Han River; and an incident in 2000, when a mortician working for the U.S. military reported he was ordered to dump a large amount of formaldehyde down a drain.
There are few scares and little gore, because the real monsters are people and from the opening scene you learn they're often American doctors.The film includes many characteristics of Bong Joon-Ho movies, such as slapstick in unlikely moments, as well as a dark turn in the second half.
A couple of chase scenes in 'The Host' could be drafts for those in his later film 'Okja' (which benefits from having a much bigger scope in the storytelling) but this film is remarkable for what they've achieved with a small-ish budget.
7/10