After having this from Netflix for a week or so, I decided I was more in the mood to watch it than Donnie Darko, and popped it in the DVD player last night. I don't watch a lot of foreign film, but the buzz on this one had been great, and the buzz wasn't wrong.
The basic high concept is that a young cop goes undercover in the mob, and a young mobster goes undercover in the cops. This is all set up in a great montage/clipped storytelling style in the first eight minutes, and we're into the movie. It is not an action movie, despite fitting nicely into the "Hong Kong" sensibilities of something like Hard Boiled or The Killer. Instead, it's more of a suspense/psychological thriller, with a strong noir tone. The difficulties of going undercover, the questions of identity and loyalty, are all dealt with very well, and there are several nice twists and turns as the story progresses to its reasonably unpredictable, bittersweet ending. Fans of Sleeper especially should check out Infernal Affairs, as there's some definite commonality of theme, tone and even some of the common story elements of an undercover tale.
I know that they're working on an American remake of this movie, and I hope that they go the route of something like The Italian Job, taking the premise only and making a completely different film, because it's hard to imagine most American film stars and directors getting this story in quite the same way.
Now I'm sort of in the mood to finally see Donnie Brasco, and Infernal Affairs also inspired some ideas for the new Spycraft 2.0 campaign I'm starting soon.