It's good that Joon-ho Bong's "Mother" is getting some exposure and generally positive reviews. A very fine film, but I prefer "No Mercy" because it's a bit more engaging from the get go and has a more absorbing premise. There's a very good external review on IMDb that outlines the plot synopsis and general characteristics of this film. For those who wish to watch the film without much knowledge, I'll give you a mini-review here.
A forensic pathologist and a young detective investigate the motives surrounding a dismembered corpse. Han Hye-jin (of "Jumong") is fantastic in the supporting role as the neophyte but talented detective who banters with her boss. The creative aspect of this film is that tension is established between the protagonists as one of them (identified early on) works against the investigation and attempts to contaminate or cover up the evidence. The characters are well-developed and the scriptwriting is clever. There are also some excellent dead body effects and one of the most convincing autopsy scenes in recent memory. This movie blends certain elements of "Seven" and "Out of Time" together to create a fantastic suspense/thriller that is quite simply unmissable.
Essential viewing. Watch it!