Messing with an icon is often a messy business which only really works when the update enhances the essence of the story or character. In that sense you might wonder what I’ve got against Sherlock Holmes as interpreted by Guy Ritchie through the medium of Robert Downey Jr. After all, Sir Arthur Conan Doyle’s famed sleuth was obsessive, bohemian, occasionally drug addled and rarely clean. His rooms were a tip, and his relationship with Dr Watson co-dependent.

Downey Jr’s cartoonish portrayal of the detective embraces these descriptors with gusto. The actor – whom I would ordinarily queue to see, and that’s saying a lot – maintains a bug-eyed, sweaty and socially inept demeanor throughout the film, punctured only by a flicker of vulnerability when his eyes graze the graceful figure of Irene Adler, his occasional lover and a bombshell in all senses.

The trouble is, this is Guy Ritchie and that’s what we get: credibility choking on style.  If Snatch, Lock Stock and Two Smoking Barrels, and Rocknrolla suggested a one-trick pony, this movie proves it. The gratuitous fight scene with its anatomically-precise brutality is vintage Ritchie and sets the stage for what’s to come: Holmes as stylish action hero, Iron Man barely camouflaged by Victoriana and well-equipped to take on the forces of evil fronted by a Darth Vader-esque Lord Blackwood. In case we missed the reference, it turns out this evil-doer is the bastard son of Sir Thomas, the aristocratic head of a black magic worshipping private members club whose powers can equally be deployed for good or evil. Thus it comes as no surprise when Blackwood murders his father in a copper bathtub, then steals a significant pinky ring.

This is Holmes, however, so black magic is inevitably exposed as smoke and mirrors. While the sleight of hand is difficult to follow in its detail, one thing is clear: both the nefarious plot and its uncovering rely on complicity from virtually every bit-player in the film: cops, prison guards, magistrates, politicians, and even the executioner himself are in on it. Of course, it’s Holmes who puts the pieces together and we’re meant to admire him for it. But we’re nonetheless left with the impression that he was aided considerably by the certainty that not a single fact was as it seemed. Blackwood’s tomb wasn’t marble, it was a crumbly composite. A prison guard wasn’t terrified: he was faking it. Even Holmes didn’t escape like Houdini: someone gave him the key. If everything is up for grabs, it’s pretty easy to cobble together a plot  – or explain one after the fact. Indeed, I had the impression that it was only once they’d reached the end of the action that the film’s writers bothered to figure out how it had all worked.

I was surprised that Ritchie had turned his hand to Holmes, and somewhat curious to see the result. (It was also a freezing January evening, I was at a loose end, and the cinema is five minutes’ walk from my house.) I’ve occasionally enjoyed his films, and Brad Pitt’s performance as a barely-intelligible Irish gypsy in Snatch was a revelation. But Ritchie is no Ang Lee, the Taiwanese-born filmmaker whose astonishing productions of such disparate movies as Sense and Sensibility, The Hulk, and The Ice Storm prove his commitment to the integrity of time, place and character are well worth the self-restraint. Instead, with Sherlock Holmes we get Ritchie’s substantial ego masquerading as vision, with Sherlock Holmes gamely trying to keep up.