Pou-Soi Cheang is one of the better genre film directors currently residing in Hong Kong. With highlights like Shamo, Yi Ngoi (Accident) and Gau Ngao Gau (Dog Bite Dog) the man has been establishing himself as a driving force behind the international recognition of Hong Kong cinema. Ai Zuozhan (Love Battlefield) is a slightly older Cheang that bears all the potential, but ever so slightly fails in its execution.
Ai Zuozhan would've made a pretty good Milkyway (Johnnie To's production house) film I think. The desaturated visuals are classy, the story is a bit grittier than usual and holds a few solid surprises and there's enough police work going on to make it a thematic peer to a slew of other Milkyway productions. It's not really an action flick, rather a tense and dark thriller mixed with a dash of romance.
The problem is that Pou-Soi Cheang has a thing for melodrama. In more recent film he's learned to balance it out a bit more, but here he crosses the line of the acceptable a few times too often. The finale for example is an exhilarating 20 minute climax, only to be followed by a mushy and unnecessary scene that takes the bite out of the ending. Cheang always compensates with style and tension, but in the end it makes the film just a tad too uneven. It's definitely worth a watch though, just brace yourself for a few overly emotional scenes that really don't belong.