There is nothing quite like a Mike Leigh film: nobody tells the same stories that he does in the same fashion that he does with the same characters that he does. He is, simply put, one of the handful of truly unique voices working in cinema (though, paradoxically, almost no other writer-director builds his stories through such a robust collaborative process with his actors), and the release of a new film under his name is always a cause for celebration even if the film isn't a slam dunk masterpiece.

And by all means, though I'm inclined to see Another Year as a half-step back from his last couple of films, it's still a great piece, essential viewing if anything in 2010 has been. As the title suggests, it takes place over a year in the life of an old married couple, environmental engineer Tom (Jim Broadbent) and therapist Gerri (Ruth Sheen), a pair of terribly well-adjusted idealists with lots of friends and 30-year old son, Joe (Oliver Maltman). Over the course of this one year, Tom and Gerri deal with the great and small issues of a number of people, of whom the most insistently present is Gerri's co-worker Mary (Leslie Manville), a low-functioning alcoholic with debilitating anxiety about being single, and a rather uncomfortable crush on Joe. Over the course of the year, we'll meet other figures, with the biggest impression being left by Tom's childhood friend Ken (Peter Wight), a sad-sack drunk to stand in contrast to Mary's manic one, and Tom's older brother Ronnie (David Bradley), facing down the miseries of aging more quietly than anyone else in the film does anything.

That rundown is about as far as the movie goes in for plot; most of its energy is given over to setting up situations for the characters to fall into, and watching to see what happens. Which is, mostly, very normal and endlessly fascinating. Given the cast involved, and their combined years familiarity with Leigh's process (only Bradley, of the main cast, has never worked with the director), no points for guessing that the characterisations are incredibly persuasive and deep, that they elude being pinned down.We need go no further than Tom and Gerri themselves to see characters who are played as very specific individuals (Sheen's performance, I'd cautiously suggest, is the strongest in the film), and yet which have enough of a core of ambiguity that makes for a thoughtful look at human behavior, rather than a prescriptive one. Are Tom & Gerri essentially smug about their perceived superiority over Mary, both because they aren't boozy wrecks, and because they deign to befriend a boozy wreck and try to save her? Or are they good friends, trying hard to pull a woman out of a self-destructive cycle and giving up when that self-destruction hits too close to home? If it's the former, are we meant to look at them as hypocrites, or just as regular people doing what regular people might do in that situation. Another Year refuses to answer these questions, which it anyway raises only implicitly; that is its great strength, that its ideas come about naturally as a result of the events it records, rather than tailoring ideas to fit into a pre-established thematic schedule (which isn't to say that the film lacks a thematic hook: it is generally about the idea of companionship, both romantic and friendly). It is exceptionally naturalistic even by the standards of its director, one of cinema's greatest living naturalists.

"Companionship", I said; by which I mean that the film is largely about the social codes by which we - specifically a certain breed of middle-class Briton, though this is clearly an example of the universal being grounded in the specific - engage with other people. Tom and Gerri dominate the film; every interaction and line of dialogue within the film tells us something about who they are; yet Another Year is, at the end, not about Tom and Gerri. The film opens and closes on shots of other individuals, who have been or are about to be affected by the central couple (the opening scene features a triumphant extended cameo by Imelda Staunton as a therapy patient trapped in a completely unsatisfying life, Gerri's polar opposite in every way): everyone in the movie expresses some facet of what it means to be around other people, behaving according to or in violation of the rules of polite society, which Tom and Gerri represent to a T. If there is a clearly-defined narrative arc, it is of Mary's violation of one of those rules, and her estrangement from the the only people that have ever thrown her a lifeline. It's telling that it's not her out-of-control drinking that causes a problem for her friends - they seem to regard it as sad but colorful - but her icy cruelty towards Joe's new girlfriend (Karina Fernandez). The final scene of the film is a tragic little vignette, with Mary trying to work her way back into Tom and Gerri's lives, and finding that it's no so easy, particularly for a woman with crippling self-doubt. Leslie Manville's expressions are heartwrenching, enough to make it clear that even here, Leigh is passing no judgment on anybody, but just laying human experience as bare as he can. Which is very bare, and painful, and recognisable.

So far, so great: the only point where Another Year stumbles is in that the whole thing feels a bit overdetermined. This is particularly prominent in its rigid structure: in each of four seasons, we follow Tom, Gerri, and the rest for about a week or so, dropping in just long enough to see a slice of their lives. It's a clever enough way to build a story, and Leigh has some fun playing around with the audience's lack of knowledge about exactly what transpired in the last three months. But it's also annoyingly schematic, and beneath the level of intelligence shown by the rest of the script. Nor is it helped by Dick Pope's cinematography, which is both extremely well-executed and ill-judged: filming each season with a different color hook (pink in spring, green in summer, brown in autumn, white in winter), and changing the lighting drastically from segment to segment, Pope unquestionably gets the point across, but the descent from the soft pastels of the spring segment to the gloomy, underlit, desaturated winter scenes begins to seem awfully rote: particularly at the end, where the combination of script and imagery couldn't possibly be screaming "Everything dies!" with less grace. Astoundingly, Leigh and Pope have conspired to find a way to make death a metaphor for death.

That's not the only misstep: some of the bigger dramatic moments are leaned on a bit too heavily, and the final shot, which would have been a real sock in the gut at half the length, goes on making its point and trying to impress upon the viewer the Immense Gravity of It All, and generally walking right up to the point where the tragic dissolves into the irritating. Thankfully, that doesn't quite happen, but it's closer than it needs to be.

Other than those problems - and they're definitely not small problems - Another Year is awfully close to a triumph: I personally didn't find it as thrillingly complete as Happy-Go-Lucky or Vera Drake, but Mike Leigh operating even at 90% is still Mike Leigh, an irreplaceable international treasure. Perfect or not, Another Year is a film to be grappled with for all the estimable things it does right.