Skimming other reviews of 1917, I have seen critics refer to it, time and time again, as a "piece of filmmaking". The term is entirely apt. For what sets 1917 apart from other war movies – indeed, from most movies in general – is its stagecraft. Arguably a higher priority than story, character, or theme, 1917's strength is its well-known gimmick: it is made to appear like one seamless, unedited, nearly two-hour shot. (Or technically two shots; there is a time cut halfway through.) On this front, it is so flawlessly executed that you may not ask for anything more.

Yes, the "one-shot feature" has been done before, most famously in the Oscar-winning Birdman. Fortunately, Mendes and cinematographer Roger Deakins avoid Birdman's self-conscious pretensions, dedicating themselves instead to creating a you-are-there experience. I don't mean this in a snarky way, but watching 1917 feels like playing, or at least watching someone else play, a first-person shooter video game.

Set during the darkest days of World War I, the plot concerns two fictitious British soldiers (played by Dean-Charles Chapman and George MacKay) who are dispatched across the Western Front in order to deliver an urgent message to a British battalion miles away: do not advance, as the Germans are lying in wait, ready to mow down 1,600 men. The stakes couldn't be higher; the path is lined with every danger imaginable. Yet the two soldiers, well, soldier on, and we are with them every step of the way.

I confess that I am as wimpy about war movies as I am about horror movies, and for the same reasons: the sudden loud noises, in this case bombs and gunfire. Because of this, I spent much of 1917 in an awful tension, looking half-away from the screen whenever things got too quiet, fearing a sudden artillery burst designed to make me jump out of my skin. I should have trusted the film more: Mendes is obviously out to deliver a classic, and isn't interested in cheap shocks. Thus you needn't worry about characters suddenly getting shot mid-speech, or landmines exploding without warning. Instead, I advise you to drink in the morbid atmosphere and marvel at how realistically production designer Dennis Gassner – himself as much of a legend as Deakins – has recreated the hellish WWI landscape.

One interesting – and potentially distracting – aspect of 1917 is how Mendes compresses both time and space. We are told that the soldiers must traverse nine miles of countryside to reach the other battalion, but given the real-time nature of the seamless presentation, there's simply no way this distance could be realistically covered in under two hours, especially given the array of Indiana Jones-level adventures our heroes have along the way. Even with unexpected bursts of acceleration from fellow soldiers and nature itself, I sense that maybe just two miles of territory actually gets covered. This compression lends a dreamlike theatricality to the film, which admittedly never purported to be gritty realism. In the end, it reminds us that 1917 is first and foremost an exercise in staging for camera and in digital compositing. In fact it is a masterclass in both. But while it has undeniable heart and soul, it tells us nothing new about the horror, bravery, and sacrifice found on the battlefield.