Why the low score?
I thought this was an excellent movie, great plot, acting, and solid action scenes. Also, Yun-Fat's English was excellent in this movie, so he was actually given a good amount of dialogue, unlike in the Replacement Killers.
Anyway, I think this deserves at least a 7.0, if not higher, and same goes for Replacement Killers, which does not deserve as high a score as this movie, but still at least in the high 6s or low 7s.