Oldboy is an exquisitely/excruciatingly imaginative revenge fantasy/nightmare...

It is surefootedly cinematic in much the same way that "Cine" City is...

It is an ultra-dark portrayal of the worst aspects of what it means to be human...

It is the Korean Memento with all the cultural pleasures/barriers that might suggest to you...

It's really much better freakin' well done than you ever might hope for an artsy foreign vengeance flick...

5 out of 5.

(Note: This movie would make the ultimate Heaven & Hell double bill with the outstanding 1998 Japanese movie After Life by director Hirokazu Koreeda -- Warning - I highly recommend that you watch Oldboy first!)