The dubbing was pretty bad. I hated the accents, and apparently they rewrote it heavily for the American market, dumbed it down badly in my opinion.
(First line of dialogue is where his mum drops the money on the dinner table.
The original just says, 'What's this? Is it for me?'
The dubbed version says 'Is this my daily allowance or what? .
The first one is so much better IMHO, because between that first and second question, he goes from innocent, curious, safe and sound, being looked after by someone who knows him and his situation, to someone giving into their greed - a tiny gamble on it being for him that goes wrong, leaves him ashamed, which he then follows up with another gamble to see if he can find the card, another gamble on the pin, until he is totally and utterly ruined by his dopamine driven behaviour)
Which brings us to the issue - there are two sets of English subtitles. One is the CC subs, which are the subs generated automatically for the hard of hearing - these are taken word for word from the dub.
The other ones are the translation of the Korean audio, as you would normally expect for a foreign movie or series. Probably worth it for most people to make sure you watch it with these.