He has made good musicals (New York, New York),surreal comedies (After Hours),satires (The King of Comedy) and biopics (The Aviator),but Martin Scorsese has never done better than the times he's dealt with life on the streets and gangsters. Mean Streets, Goodfellas and Casino (and, to some degree, Taxi Driver) are proof of that. It doesn't seem strange, then, that his finest film in over a decade (Goodfellas was released in 1990) sees him return to that familiar ground. With a few changes.

The Departed, based on Hong Kong thriller Infernal Affairs (2002),is Scorsese's first gangster film not to feature Italian-American criminals. In fact, this film is set in Boston, where the Irish rule. One of these "godfathers" is Frank Costello (Jack Nicholson),the man the State Police want the most. After years of investigation, they're finally getting close, thanks to undercover agent Billy Costigan (Leonardo Di Caprio). Because of his family (all Irish, all bad),becoming a member of Costello's crew isn't that difficult. Now all Costigan has to do is report to his superiors, Queenan (Martin Sheen) and Dignam (Mark Wahlberg),who will pass on the information to Ellerby's (Alec Baldwin) Special Investigations Unit. What they don't know is that Colin Sullivan (Matt Damon),the most promising element of said unit, has been on Costello's payroll since he was 12. Soon enough, both cops and crooks become aware of the situation, beginning a manhunt that's gonna make the already fragile Billy even more nervous and Costello increasingly crazier.

By moving from Hong Kong to Boston, Scorsese and screenwriter William Monahan have made the first step in ensuring this film will be quite different from its Chinese inspiration. Another significant factor is the running time: a mere 97 minutes for Infernal Affairs, 150 for The Departed. This is due to new characters (Dignam and Costello's henchman Mr French, played by Ray Winstone, were missing in the original) and subplots, such as the one concerning Madolyn (Vera Farmiga),a psychiatrist who gets emotionally involved with both of the moles. But the most crucial difference is in the depiction of the underworld: whereas IA was stylish without being excessive, Scorsese's vision comprises very colorful language (some insults are so creative one might expect Joe Pesci to show up) and, of course, buckets of blood, the last part of the movie proving to be particularly shocking. None of the scenes ever reach the gross-out level of Casino's head-in-the-vice scene, but in pure Scorsese tradition it remains unflinchingly violent (also notable is the music, perfectly setting the mood, scene after scene, alongside Thelma Schoonmaker's impeccable editing).

Amidst these brutal surroundings, the director handles a spot-on cast: Baldwin, Sheen and Wahlberg (the latter finally back on form) make good use of their little screen time, Damon fine-tunes the edgier side he showed in The Talented Mr Ripley and the Bourne movies, and Nicholson, playing the villain again at last, delivers another OTT but classy turn (original choice Robert De Niro would probably have played the part with more calm and subtlety). A special mention is needed for Di Caprio: working with Scorsese for the third consecutive time, he has finally found a way to shake off his Titanic image, thanks to a vulnerable, gripping (and arguably career-best) performance.

With its clever plot, excellent acting and expert direction, The Departed is without doubt the year's best film so far. If this really is going to be his last gangster film (he has said so),as well as his last studio-endorsed picture, Scorsese can be proud, given the masterpiece he has given us. If only they gave him the Oscar in return...

Blood Diamond (2006) was the film which turned me into a fan of Leonardo DiCaprio, and he must have been on a roll that year as The Departed (2006) was not only made that year, but is just as good as Blood Diamond with again phenomenal acting from almost all.

The good and the bad:

• The film is 14 years old at the point of writing this, and is still as good as the day it was released first saw it.
• The acting is phenomenal with the award (in my opinion) going to Leonardo DiCaprio .
• One of the beauties about this film is: Just as you think you've grasped what is going on it throws another twist in.
• The only let down for me (and it is minor irritation) was Matt Damon, whom I'm not a fan of or his acting.

Martin Scorsese returns to familiar territory with this story of the lives of cops and gangsters living in America. However, a few things are different this time around – it's Irish gangsters rather than Italian, and for the first time in his life, Scorsese is shooting a remake, of the Hong Kong film INFERNAL AFFAIRS. I haven't yet watched the original film but I'm pleased to say that THE DEPARTED is an example of the director at the top of his game and I'm completely satisfied that he finally won his best director Oscar for his efforts here.

To say too much would be to spoil the experience. Cinematography is spot on and the ensemble cast fantastic – headlined by DiCaprio, playing it on the edge as the undercover cop, and Damon as the hateful cool cucumber, a con on the inside. Jack Nicholson plays it OVER the edge as a past-his-prime gangster; gradually losing his marbles in a world of violence, while Ray Winstone's heavy is another weighty performance from this underrated star. Kudos to newcomer Vera Farmiga for holding her own among the established talent and Martin Sheen for taking a small role and running away with it. Mark Wahlberg also deserves mention for his Oscar-nominated supporting role as a foul-mouthed cop, the best of his career.

The plot twists and turns and is chock-full of Scorsese's trademark violence, with bloody shootings and beatings taking place throughout. The story is complex, forcing the viewer to give the film their full attention, so the 2 ½ hours just fly by as you're watching it. Things culminate in what I think is a very effective, brutal, shocking, sudden climax, which some people have criticised as being too rushed and too violent, but which I think is perfectly realistic, an example of how a house of cards can come tumbling down so suddenly. A perfect ending to a perfect film – and a must for all fans of twisty thrillers and gangster flicks.