I can see why they called this film 'The Wailing': it is literally two and a half hours of people wailing/crying/screaming unnecessarily. It has a great premise, but all of the tension is removed by continuous and histrionic wailing and bawling.

It would also have been a better idea not to have cast Korea's answer to Homer Simpson in the leading role. I honestly didn't know whether the film was trying to be a thriller or a comedy at some points.

I would most definitely recommend that you give this one a miss.

Indeed a very clever film. You need to see it 2 or 3 times to see the clues and understand the story fully. A tales of light vs. dark and how evil manipulates people.

The theme of the film is about impotence of human beings when facing the phenomena that cannot be explained with reason. Mysterious things happen in a small town in Korea. Science does not seem to give the townfolks a satisfactory or believable explanation. People start relying on religions like Christianity, folk shamanism, etc. But the involvement of those religions seem to aggravate the phenomena. Besides, their exorcism and explanation seem to be as mysterious as what has happened to townfolks. The film depicts ordinary people who slowly walk into the unavoidable doom, whilst wandering around doubting everything. The film is ultimately about belief and faith. But this film is not praising them. Rather, it shows how petty such belief system is. At one point, the film surpasses the rather clichéd questions: science or religion? Belief or reason? Which religion is right? Instead, it shows the fundamental limitations of all human beings. In total chaos, what should we believe and what can we do? And, there, the ultimate source of horror lies in. Because the answer is 'We don't know.'