Before Christmas, I attended the press junket for The Spirit, Frank Miller's adaptation of Will Eisner's classic 1940s comic book stories. I don't do as many junkets as I used to, so it was a pleasant enough novelty to turn up at a posh Central London hotel, find the block-booked suite of rooms with the film poster displayed on an easel outside, sign in and wait for my allotted interview slot with stars Samuel L Jackson and Scarlett Johanssen (or at least for an allotted slot, traditionally an hour or two after your allotted slot). Usual drill: help yourself to coffee and soft drinks and pastries, chat to other film journalists - in this case, a nice chap called Nick from Empire - with whom you compare waiting times with rolled eyes. ("How long have you been waiting?" "Who are you doing?" "Sam and Scarlett." "Not Eva?" "No." "I'm just doing Eva." "Ever done Sam before?" "Yeah, he's always good value" etc.) Here's the big difference: none of us had seen The Spirit. And by none of us, I mean the journalists, the PRs and the actors. The Spirit, we were informed, despite being mere weeks away from release, wasn't ready.

This lent an odd hue to the whole experience of being led into another suite for your allotted slot with Sam and Scarlett. The etiquette of junkets is this: meet star, tell star how much you love their new movie, talk to them about their new movie, all the while looking for your chance to seamlessly move off their new movie and onto their old movies. On this occasion, the conversation about The Spirit was limited to speculation. They showed us a few minutes of footage in the green room, which gave us an idea of what it would be like, but no more. Samuel L Jackson, whom I've interviewed before (for Jackie Brown ten years ago), seemed particularly agitated by the process of talking about a film nobody had seen. The upside: it was easy to get off the new movie and onto the old movies. Because at least we'd seen the old movies.

I've never experienced this before. It was rather surreal. As I was reviewing The Spirit for Radio Times and in Mark Kermode's stead on 5 Live, I assumed I'd see the film before it was released. I didn't. The film company, Lionsgate, were unable to provide a screening. Instead, just before Christmas, we received an email telling us that, "due to late delivery", a screening was not practical. So I paid my money and went to see it on Friday morning at an otherwise empty mulitplex except for three teenage boys, who sat in the back row.

I wonder what they made of it. I really liked Sin City, Frank Miller's previous outing in this graphic-novel-for-the-screen format, so would ordinarily have been looking forward to The Spirit. However, not screening a major film for the press always carries with it an eggy smell. I'm sure "late delivery" was the very reason we weren't shown the film in advance, but it puts a real pole in the spokes of all the pre-release press for The Spirit, which will have been written without the writer having seen the film they were writing about. I certainly filed my copy to Radio Times without any meaningful qualitative description of the film, and instead ran it as a more general Q&A. Guess what? The film's a dud.

I admire Miller's pioneering technical prowess - shooting actors against green screen and dropping them into digital environments in post-production, in the spirit of the 2D original - but this cannot carry a film alone. He provides some truly beautiful frames, but the action itself is hampered by two things:

1) The lack of courage and conviction in "updating" the 40s style to include mobile phones and video and computers, while putting all the women in wartime hats and using the classic 40s pulp-noir delivery (one or the other, surely?).
2) The uneven direction of the actors. Having actually spoken to Scarlett Johanssen about the process, it's clear that Miller storyboarded the action to within an inch of its life - as you'd expect from a comics master - but allowed the actors a lot of freedom, at least within the ludicrous confines of acting against a green screen and hoping for the best. This is why - perhaps understandably - Samuel L Jackson is totally off the leash, making the Octopus a composite of every other part Jackson has played, except cranked up to 11. He looks tremendous (everybody looks tremendous), but the acting is so over the top, it threatens at every stage to topple the film over into a ditch. Johanssen clearly has no idea how to play her vampish-nerd-sidekick Silken Floss and comes across as embarrassed. The brief given to Eva Mendes was obviously "Be sexy" and she pulls this off, but all around her, actors seem unsure how realistic or cartoonish to play their parts.

The result is a relentless cat and mouse plot that gathers no momentum and no empathy. Who cares what happens to any of them? This is not a given with comic book adaptations: I cared what happened to everybody in Spider-Man and Iron Man and Batman Begins. There's something about Miller's flat, drawn-in methodology that puts caring out of reach.

Oh, and it all ends in an escalating shoot-'em-up, with big guns blazing. Hardly in the "spirit" of the original, and such a lazy way of attempting to keep the teenage boys onside. Surely the acres of cleavage will have done that job.

What becomes clear in retrospect is that Sin City was as much a triumph of Robert Rodriguez - a director of actors by trade - as of Frank Miller. It was so much better than The Spirit - leaner, more impactful, content-driven, more drawn and yet more fleshy. Miller will ride again, but in adapting something sacred from 60 years ago, he's killed it with modern tricks. The likes of Persepolis and Waltz With Bashir are clear indicators that not only does flat animation work, emotionally and narratively, people will actually go and see it. Maybe his next film should dispense with actors altogether and go old-school. Living, breathing human beings are clearly outside Miller's comfort zone.