The hype is right about one thing: The Departed is certainly a return to form for Martin Scorsese. There is however a difference between returning to form and returning to peak form, and this is where the remake of the much-superior Infernal Affairs can't quite justify all its praise: it is stylish and fun, but fairly empty when all is said and done.

Here is how Scorsese proves to you that you are watching a Scorsese film: within the first two minutes, we have seen a winding tracking shot move around and into a storefront as the Rolling Stones' "Gimme Shelter" blares on the soundtrack. Watching The Departed is experiencing that moment over and over again, as it becomes clear that the justification for the film is watching Marty do Marty. And don't get me wrong: nobody does it better. Except Marty himself, who has done it better several times in the past.

The plot twists and snakes for the entire 2.5-hour running time and is therefore impossible to recap, but the situation is thus: Colin Sullivan (Matt Damon) is a gangster who has infiltrated the Boston Police Department. Billy Costigan (Leonardo DiCaprio) is a policeman who has infiltrated the gang. On the side of the police we find Capt. Queenan (Martin Sheen) and the foul-mouthed Dignam (Mark Whalberg); their opposite is Frank Costello, played by JACK NICHOLSON, yes, all in caps like that, because there have been very few times when a Jack Nicholson performance has been so...big?

Discussing The Departed necessarily means discussing Jack's performance. The man loves playing villains. We all know that, and we often love him for it. But from time to time there is a role in which he gets so camped-up and intense that it becomes a liability, and this is a grand example of that. I do not know how a director like Scorsese allowed such an imbalancing element into his film, but it is there, and it is scary. Perhaps Nicholson's desire was to play for the role's negligible comedy. Perhaps he found it funny to speak with a Boston accent, and couldn't concentrate. All we have to go on is the performance, which is not really part of the rest of the film: whatever is left to chew on after the scenery is all gone, that is what Jack is chewing in. If it weren't so shockingly inappropriate, it would be hilarious.

The rest of the performances range from decent to great, and it's unfortunate that the lower end of that spectrum is populated by the leads. DiCaprio and Damon are both fine actors, but they are not particularly well-used here, mostly because they are not very well-written. In Infernal Affairs, Andy Lau and Tony Leung played conflicted men who lose their identies and then find them again, except that their new identities are not entirely right - it is a film of surprising moral depth, for a Hong Kong cop picture. In The Departed, Costigan and Sullivan are respectively a lapsed-Catholic and a more-lapsed-Catholic. It is a Scorsese film, after all, and Catholic guilt is the central theme of just about every great film in his career; but Catholic guilt is not the same thing as moral pressure, even when it is a component, and there is nothing but guilt driving the lead characters.

Sheen and Wahlberg and the terribly undersold Alec Baldwin are all much better. It's becoming more and more obvious these days that Baldwin is a terrific supporting player: he can't help himself but to steal every scene he's in. As the FBI agent in charge of a sting against Costello's crew, he is playful and lewd, and just when one could be forgiven for wondering how he came to be in charge of anything, he becomes dominating. His delivery turns the line "the Patriot Act - love it!" into the best moment of the film. Sheen and Wahlberg don't hit quite the same heights, but they're both fine at playing decidedly clichéd parts, even though Sheen sometimes seems to be chanelling President Bartlet.

But let's be honest: the star of the movie isn't an actor, it's Martin Scorsese. After barely managing to convince myself that The Aviator was worthwhile and failing to even see Gangs of New York, it's a breath of fresh air that The Departed is pretty self-evidently good. It's just that it's not great, and that's kind of scary. It's easy to accuse most of the last 15 years of his career as being the result of a man far outside of his comfort zone, but here he's squarely in his usual territory, and the results lack the energy and invention of his best films. It looks and feels like a Scorsese picture, but watered down, like a group of film students mounted a shot-for-shot remake of Mean Streets. There's nothing here he hasn't done before, and towards the end when things turn violent, it starts to run out of steam entirely, as though Marty has actually come to the point where he doesn't want to shoot gore anymore. Which is his right, but then he should go ahead and not shoot gore, rather than let the film go so flat during its climax. Ending the film as he does with a "cute" visual pun just borders on insulting. And it's worth mentioning that I've now seen something I wouldn't have imagined possible: a Thelma Schoonmaker-edited scene that was distracting and ill-conceived.

Still, it was fun, and the butt-numbing running time flew by. I just wish that I didn't have to praise one of the great moralists of modern American cinema by proclaiming his film to be "fun."