I want to start by saying this: if you're a fan of Jackie Chan's usual slapstick acrobatics and comedy that doesn't mean you should shy away from this film. Yes, many of those movies are great but it's also nice to know he can...you know...actually act. Just think of it like Robin Williams doing One Hour Photo. Sure, you knew him as Mork, but he was absolutely perfect for his role in One Hour Photo as the insanely creepy photo lab guy. And so it goes for Jackie Chan. His bread and butter will always be goofball kung fu films but man...he can definitely act if he has to.
In terms of plot there really isn't much you haven't seen before in this film. If you've ever watched a movie about a guy crossing the Yakuza while trying to get the girl, not a whole lot will be new here. I did like the added sense of unity that most Yakuza movies lack with all of the Chinese immigrants. Also, the film touches on the often tenuous relationship that China and Japan share. That's not usually presented in a realistic manner...maybe in Jet Li's Fist Of Legend (still one of the best kung fu flicks to date in my opinion), but that's more of a period piece. And forget about all of those Men Behind The Sun films...while they may be somewhat accurate they're more like snuff films than a real historical look. This may also be (to my knowledge, anyway) Jackie's first Category III movie (for westerners who are unfamiliar, this would be the equivalent of the US's Unrated status or maybe the UK's 18 rating. And I think the Aussies have MA-18? Whatever). So it took Chan until his 50s to make a movie with enough substance to carry such a heavy rating.
I'd definitely recommend this for Jackie Chan fans...especially the ones who started to feel like they'd gotten a bit tired of seeing him doing the same "awe shucks" good guy hero thing. Don't get me wrong...Dragons Forever ranks right up there for me among kung fu films, but you can only milk that for so long, you know? Hell...even Adam Sandler moved on and, let's face it, he's not the most mature guy in the world. But Chan succeeds where Sandler failed...he proved he can be counted on in a dead serious role and deliver as good as ever.
