The yanks have tipped their gunk into the Han river and what emerges is like a bulbous, amphibian t-rex with a set of expanding flabby chops rather like the Predator (but flabbier).
Gwoemul is an original mix of nice-looking Korean arthouse horror, political satire and slapstick comedy. When these elements hang together well it's gripping; when they don't, it isn't.
Indeed the pacing is generally quite uneven, with the monster's importance to the story waxing and waning over the two hour running time. Plenty of people die as a result of their interactions with it, but not in the deliberate, economical way normally associated with predation.
The farcical elements to the scenario felt at times as if they were there to cover up what the literal-minded would take to be the weaknesses of the plot. Yet perhaps the comic interludes are more effective for native audiences.
Anyway, there are some very atmospheric moments, generally those which take place under bridges and inside the Seoul sewer network. And it picks itself up for a great, and ultimately quite daring, conclusion.