Infernal Affairs II is one prequel you definitely shouldn't see before the original - so much of the interest comes from spotting throwaway details that assume more importance in the original film, and the character revelations are far more fascinating if you've seen the original. Take the opening monologue: standard enough - until you see who it is that Inspector Wong is opening up to: what we know about their eventual fates and the implications it has about their relationship is far more intriguing than if you choose this outing as you starting point.
With no Andy Lau or Tony Leung this time round, their younger selves played by the lacklustre Shawn Yue and Edison Chen are sidelined in favor of their superiors. It's a wise decision: Tsang and Francis Ng are superb, although curiously Anthony Wong isn't as good as in the original in a more expansive and more morally compromised role. The first half hour is awkward, but the deferred violence following the death of the local triad boss is well handled and the film fires into life with some genuinely great filmmaking once the consequences start catching up with the various characters.
The influence here is clearly the Godfather films, but whereas Godfather II was ultimately just a typical sequel exercise in underlining and escalation, this back story really does add layers to the original, with Eric Tsang becoming a genuinely tragic figure in his final scene. Where Godfather II tended to use history merely as a backdrop, here the handover of Hong Kong becomes an integral part of the film. The final montage of power being handed over from one nation to another, as police badges are replaced alongside criminals photos on the wall carries real weight and substance: it's what the film is all about - the loss of authority and the gaining of power, given the feeling of a requiem rather than a triumph by Chan Kwong Wing's eloquent score. Not as good as the original, true, but still very impressive indeed.