Michael Mann's name is usually breathed in reverent tones along with those of Peckinpah, Fincher and a host of other directors whose work is known for quality and machismo. And if you watch Heat, Collateral or The Insider you can see a modern master at his best.

So it's with a please-tell-us-it-isn't-true tone that you can hear his fans desperately trying to find something to like about Public Enemies. Like Ali and to a much greater extent Miami Vice, Mann's filmmaking technique is flawless, his attention to period detail in 1930s Chicago and the Midwest picture perfect.

It's hard to say what's missing because there are so few instances in the film where you can pin it down. There's just a sense of emotional intensity, humanity and engagement not being there - ironically considering the film's about the at-times deadly cat and mouse game between modern Robin Hood figure John Dillinger (Depp) and straight-laced early FBI agent Purvis (Bale).

There are also problems with the plotting, pacing and dialogue. However historically accurate it is, the story seems to be an endless string of the newly minted federal agents just missing Dillinger by a hair's breadth, or his busting out of the joint when they do get him.

It's the story of a whole host of gangsters of the period from the business-aware Frank Nitti to the borderline-psychotic Baby Face Nelson, but somebody (the studio would be my guess) chose to zero the marketing in on Depp as Dillinger, the script making him a virtual folk hero and painting him in as favourable a light as possible.

He sweeps coat check girl Billie (Cottilard) decisively off her feet ('You're with me now') and despite the way he makes a living, she can't help but love him.

But the new breed is taking over, running numbers rackets out of dingy secret rooms making the amount Dillinger makes in a bank score many times over every day. Dillinger's kind is an endangered species, and in a series of increasingly close shaves which really give the sound artists free reign as Tommy guns and shotguns shake the theatre and splinter forests and buildings, the G men close in, letting Dillinger slip through their fingers from lack of experience despite brute force.

But when all's said and done, you won't have any more a sense of these people than you had from vague cultural awareness, and the plot doesn't make it worth your while either.

Most intriguing of all is how they managed to spend $150m. While the sets and costuming are top notch, Mann shot it all on digital video and most of it is urgent, twitchy handheld. Are Depp and Bale worth that much after The Dark Knight?