I enjoyed Sukiyaki Western Django, but for me this completely blows it away.. and then takes a finger.
Song might steal the movie (and rightfully so, he's fantastic in it), but Byung-hun was my favorite of the trio. I now officially am looking forward to one aspect of the GI JOE movie. Jung Woo-sung's Good was solid, though his character didn't really get any of the fun, quirky little beats that the other two do, but makes up for it with some awesome gunfighting/stunts (zip lining around the Ghost Market was a blast).
I wouldn't call the opening lackluster - Song's 'introduction' on the train is classic and there are some really great bits of action (thug barreling down the train only to be blasted straight back out a doorway by Woo-sung, the impact rocking the camera, his little rifle twirl on top of the train before nailing the guy on horseback, spear tosser), but kind of agree with Spike that the movie doesn't hit it's full stride until the knife fight. And completely agree about the Indiana Jones thing, that was in the back of my mind during the entire chase sequence.
Also - everything after Song is drugged and wakes up with the kids is brilliant. Perhaps he's a pervert?
It might not have reinvented the genre, but did it need to? Love this one up and down, start to finish. Any idea when/if this will see a proper dvd, or dare I wish.. blu-ray, release?