Great, but can't better the original.

Rating: 7/10 (29 April 2007)

First things first. I watched The Departed before watching Infernal Affairs. So I had absolutely no idea of what to expect from TD.
Colin Sullivan is a criminal undercover in the Massachusetts state police. Billy Costigan, conversely, is a police officer working undercover in the ranks of big shot Irish American gangster Frank Costello. The tension rises as Sullivan is assigned to discover both the mole inside the police and the mole in Costello's crew -- while Costigan tries desperately to discover Sullivan's identity.
Dicaprio turns in a great performance as the tough-as-nails Billy Costigan. Damon is also great as the more laid-back Sullivan. But the best performances come from Mark Wahlberg as hot-headed staff sergeant Dignam and Jack Nicholson as the irredeemable Frank Costello.
But great performances can't elevate the Departed to "Infernal Affairs" levels. The movie is full of pointless subplots (such as the love triangle between Madolyn, Billy and Colin) and re-imagined scenes which can't hold a candle to the originals. Queenan's death, for example, is nowhere near as gut-wrenching as the death of SP Wong in Infernal Affairs. The music ("goodbye, policeman") and suddenness made that scene a real tear-jerker in IA, while the decision to film Queenan's descent in slow-motion damaged unexpected nature of the character's death.
It was also a bad idea on Monahan's part to combine the two female characters from IA into one. That Costigan and Sullivan would be seeing the same woman is far too improbable.
The ending of TD isn't particularly well-written or directed. Adding another corpse to the elevator bloodbath was unnecessary and made the scene almost comical as the body count increased. The decision to kill off Sullivan at the end was another mistake, negating the entire point of the original story.
My main problem, however, is the complete alteration of Yan and Lau's characters. Lau in IA is a decent, albeit misled man who wants nothing more than to leave organised crime behind. While Yan is an internally troubled individual desperate to regain his identity. In TD, Sullivan is almost a comic book villain, working for and against everybody. While Costigan is a wacko who kills people for no apparent reason.
It's also worth mentioning the scene where Costello's gang meets with the "Chinese government" guys. Is the extremely negative portrayal of the Chinese (complete with various racial slurs) Hollywood's way of repaying the very people who gave birth to the script?