Really dumb and schlocky but endlessly entertaining and fun to mock.

As my interest in film has grown, I've taught myself not to get caught up in the hype surrounding new releases. The way that films are marketed today is designed to get you as intrigued as possible with a minimal amount of meaningful information, something that often results in disappointment. No matter how good the film turns out to be, it cannot ever perfectly resemble the picture we have built up in our minds from endless exposure to trailers, photos and magazine features.

With Iron Sky, I made an exception to my rule. The idea of a crowd-sourced, modern-day B-movie about Nazis hiding on the Moon seemed so absurdly brilliant that I had to see it. Having followed the film's progress via Kermode Uncut and the official newsletter, I went as far as writing to the film's distributors, complaining that I couldn't see the film on the only day when it played in my then-home town of Newcastle-upon-Tyne. Finally I saw the film on DVD, and was promptly given a taste of my own medicine - because Iron Sky is perhaps the biggest disappointment of 2012.

What makes it so disappointing is that the premise of Iron Sky is so damned irresistible. The very phrase "Moon Nazis" conjures up feelings of glee; it's a notion or setup that is so ridiculous that it just has to work on some level. As I mentioned in my review of The Boys from Brazil, Nazis have been reliable pantomime bad guys for decades, with Moon Nazis following swiftly on the heels of zombie Nazis in Dead Snow. Add in the presence of trash veteran Udo Kier (most famous for Andy Warhol's Flesh for Frankenstein) and you have the makings of a genuine oddball gem.

Iron Sky is at its most basic a high concept B-movie. It has a trashy story with broadly drawn characters built around a single idea - in this case that Nazis hid on the dark side of the Moon in 1945 and are now planning to return to Earth to stage an invasion. Being a high concept film we know from the start that it might not sustain its premise or promise, but what's startling is just how quickly the film drops the ball. Where Indiana Jones managed to take hackneyed components and make them feel fresh and exciting, this feels like it's desperately trying to ditch its B-movie baggage, like it doesn't really want to be about Nazis at all.

The biggest problem with Iron Sky is that the story that the filmmakers settle on completely ignores or overlooks all the most interesting aspects of the central concept. The most dramatically intriguing aspect of the central idea is how the Nazis would have got to the Moon in the first place, and how they survived for so long. There are a great many science fiction films about humans stumbling upon ancient civilisations (Prometheus being a recent example), and this film could have told that kind of story from a different, less expository perspective.

Having Nazis on the Moon raises all kinds of questions that could have been answered very creatively. How did they survive to create a fully functioning space colony on technology lifted from gramophones and Volkswagen Beetles? How was their social order reshaped after the death of Hitler? We get a certain amount of insight into their understanding of Earth, with schoolchildren being shown a severely edited version of The Great Dictator, but this could also have been explored in greater detail. Rather than being about the act of coming to Earth, Iron Sky should have stuck with the lunar astronaut staying on the Moon, acting as our way in to this bizarre and intriguing civilisation.

With this opportunity being swiftly squandered, the film could at least have used the arrival of Nazis on Earth to give us a half-decent fish-out-of-water story. There are moments where this thought comes through, such as the remarks in the stolen VW van or when Renate wanders out of the cinema, having finally seen The Great Dictator in full. But for the most part the film ops for comedy so broad it's insulting, epitomised by the running gag about the black astronaut having been turned white. In Bubba Ho-Tep, that kind of joke was a funny little throwaway which added to the overall charm and absurdity of the plot; here it's overplayed so much that it just smacks of desperation.

Speaking of desperation, the film's attempts at satire all fall flat. B-movies have a rich history of sending up contemporary social and political attitudes, but Iron Sky aims so low that in places it resembles the Scary Movie series. Having the US President be a stand-in for Sarah Palin is fine, but this isn't developed in any meaningful way; the film just makes the same old jokes about her being an idiot and presidents waging wars to get elected (Wag the Dog, anyone?). The film's pop culture references are already dated, and when the characters resort to ripping off the 'angry Hitler scene' from Downfall, you know they've run out of ideas. At its worst moments Iron Sky can feel like a bunch of lazy Europeans shouting about how dumb Americans are, in a classic case of the pot calling the kettle black (or should that be white?).

A further indication of how far short Iron Sky falls is found in its profanity. The film is a 15 certificate, and being an action B-movie we don't expect the characters to always talk with decorum and restraint. But very soon the film comes to rely on its swearing to define itself, a tactic that backfires for two reasons. Firstly, there's nothing so shocking or outrageous that the film becomes defined by it - there isn't the equivalent of Hit-Girl using the c-word in Kick-Ass, which was also a 15. And secondly, the swearing isn't used to build up the characters or convey genuine emotion, as it is in something like Sexy Beast. In the end it's all sound and fury, signifying nothing and making the characters look more pathetic than tough.

As for the characters themselves, they're all something of a disappointment. The Sarah Palin shoe-in (Stephanie Paul) is completely naff and flat; at times she resembles a porn star trying to act, complete with too much make-up and stilted delivery. Her aide Vivian Wagner (Peta Sergeant) spends much of the film as a vamp with no real motivation, and her final costume feels like it was ripped off from The Hunger Games. Renate gets a little more to work with but still has to spend much of her time either playing second fiddle or just being half-witted. As for the men, Götz Otto is unmemorable as Klaus Adler, Tilo Prückner phones in the Metropolis¬-style mad scientist, and Udo Kier makes the most out of a very small role, something in which he has great experience.

What makes Iron Sky so heart-breaking is that all of its major problems could have been so easily fixed. It wouldn't have taken a lot to flesh out the characters a little more, whichever story or setting they had opted for. The satire could have been strengthened and made a part of the film's underlying themes, with the jokes punctuating rather than puncturing the tension. We could have ended up, in other words, with a film with all the calibre and character of To Boldly Flee, instead of a horrible mish-mash of half-realised ideas that never come together in a meaningful way.

The only aspect of Iron Sky that really gels together is its effects. With digital technologies becoming steadily cheaper and more accessible, it might seem fruitless to praise the effects work - not to mention the speed at which CG technology advances. But even with this caveat Iron Sky does boast a number of memorable spacecraft, particularly the enormous Gotterdammerung which rises from the Moon base in the last act. The battles aren't as engaging as those in To Boldly Flee, because we don't care about the characters, but purely on a technical level they are executed in an efficient and visually professional manner.

Iron Sky is a crushing disappointment on almost every level. Its impressive effects are not enough to redeem the film of its meandering plot, paper-thin characters and tired, lazy humour, all of which conspire to turn a fantastic premise into a truly dismal failure. The Boys from Brazil offers far more laughs, intentional or not, and Dead Snow makes a little more of its central concept than these filmmakers managed. Nazis on the Moon was a great idea; a better one would have been to leave them there.