I have seen john wick twice, once before watching Oldboy, and once after.
On my first viewing, I loved the film. The scenes at the start which kick-start the plot were so unexpected and shocking that I immediately wanted John Wick to go out and kill many, many people.
The film was not plot heavy, but it wasn't really about the plot, it was about the action scenes, and the action scenes were beautiful. The styling of the action scenes, were it pulls away and creates a dynamic movement, that's elegant and precise, and isn't cut to shit, so you can actually see what's going on, was amazing to me at the time. The nightclub scene alone is one of the most incredible pieces of action cinema that I had scene. The action styling was perfect, it didn't reduce impact and cut away for a PG-13 rating, and the way in which it dimmed the sounds of the violence and turned up the music made it seem almost like a dance. and the world building, I was fascinated by this world, the golden coins and the hotel and all of the little intricacies laced into the movies were incredible. In short, I loved this film first time around.
Then I watched Park Chan Wook's Oldboy.
Oldboy is a masterpiece.
On my second viewing of John Wick I was viciously let down.
After the first fifteen minutes in which the events that kick-start the plot take place, the plot ends. That's it. After that john wick kills people, for an hour and a half. Even the world building that enchanted me so much the first time around fell flat, on a second viewing it just seemed rushed, and only existed so that john could kill somebody else, it was a means to an end, and that showed.
John Wick, people could argue, isn't about the plot, it's about creating a clean stylish action flick, with stylized, yet unflinching and realistic violence. But to those people I say: have you watched Oldboy. Everything that makes the violence in john wick so good, came from Oldboy, the dulling of the impact, not clear and precise, but thick and realistic, comes from Oldboy. The long action takes, the gorgeous action choreography, all from Oldboy.
The other thing that Oldboy has that John Wick doesn't, is plot. Now, the clean stylish action flick is fine by me, but if it's as unoriginal as john wick, and everything in it has been done many times better, in a movie that didn't sacrifice plot for violence, and delivered masterfully on both, just don't bother, watch Oldboy. It has a plot, and fight scenes cooler than the ones in John Wick, where enemies don't feel the need to come one at a time so John can pick them off.