Once Upon A Time (2008)
The Koreans make some cute and whacky stuff as well as some rather melodramatic shows, and this is definitely in the former camp, with the Korean kind of humor, a little of the the three Stooges, plus some bits borrowed from a few classic heist stories, flavored with a bit of the "Thieves Like Us" genre, with some Spy vs Spy bits and finally a decent dollop of romance thrown in too.
This all could backfire, but the Koreans pulled it off to make a rather enjoyable hour plus worth of distraction, and if you are a big Korean movie fan, esp of the genre like the Good, the Bad and the Weird sort, this will suit you to a tee. Forgot those tear jerkers where everyone dies, and sit back and enjoy the twists and turns as thieves, singers and patriots all try to steal this jewel known as the "Light of the East". Set in the end days of WWII in Japan occupied Korea, it probably brought a lot of joy to Korean viewers, but for the non partisan audience, the humor, action and wit plus the bits of action thrown in will give you plenty to smile about.
Chick factor: Korea manages to churn out these awesome beauties, and the femme fatale in this show (Lee Bo-young) does heat up the room whenever she appears: 4/5
So, a rental or keeper?
I reckon if the genre is right, this movie will give you more than one viewing, so buy it....