As headline says, its iconic.
Is it good? Yes, if you like Z-tales.
Predictable and I wish the jerks had worse endings.
I personally aint very fond of Z content but I endured this one, mainly because the acting was that good.
It was the perfect Z-popcorn excitement cine you watch with friends.

I wish the ending was a little bit better but all in all, it was quite good, again, its the acting that raises the rating, script wise, not as much .

Perhaps contradictive but it has 99% good re-watch rate as the Fx and all the small details you might miss the first round.
Another small interesting part is that the movie is 2hours long, which makes the story almost in real time (as a regular Soul-Busan journey takes ~2.5hours with the speed train), for that alone, it makes this worth watching.