At some point, I'd really like to see John Carney make a different movie, since he's clearly got talent to spare as a director of actors, and his writing is an irresistible combination of aching sincerity and clear-eyed, raw naturalism. But as long as the one film he keeps making over and over again - this third incarnation is called Sing Street - continues to be executed with such graciousness and sweetness, I suppose it's not doing anybody harm.

This time, Carney's story about falling in love and crafting music, not necessarily in that order, has an autobiographical tang: it's about a teenager in 1985 Dublin, Conor Lalor (Ferdia Walsh-Peelo), right about the same age that Carney was at the same time in the same city, and they get interested in the same music. But for Conor, music comes into his life only accidentally: one day, he spots a beautiful older girl, Raphina (Lucy Boynton), and to come up with a reason to talk to her all casual-like, he asks if she'd be interested in acting in the music video his band is preparing to shoot. Conor, it should be pointed out, is not in a band, does not know how to play an instrument, and cannot sing.

Describing the plot in any more detail would run the risk of breaking it; I assume you can figure it out, anyway. Boy scrounges up fellow social rejects from his punishing Catholic school, boy discovers that there is profound joy to be found in the act of creating music, boy starts to explore his own identity through the music he begins to explain. Boy also gets girl, which is frankly almost incidental. As in Once and Begin Again, Carney is mostly interested in the process of music, how easy it is to get caught up in and lose a bit of yourself in the act of creation, and all the ways in which that can be therapeutic. This time around, he switches things up a little bit: with the characters dazzled by this new thing called "music videos", the focus is as much on how Conor visualises his music as how he conceives of its sonic qualities. If these "making the video" scenes aren't quite at the level of cinematic inspiration as anything in the other two movies - the piano shop scene in Once would be almost impossible to match or beat, anyway - there's still much charming about watching the kids in Conor's band fumble about enthusiastically with cameras they don't quite know how to work and instruments they can't quite play. Initially, at least; if there's one completely damnable sin the story commits, it's that the band becomes much too good much too quickly, writing suspiciously accomplished originals within weeks of starting out and more or less completely mastering their instruments by their second gig. It's unbelievable fantasy relative to how muted and everyday the whole of the rest of the film is, and it robs it of much of its relaxed relatability.

It would take an enormously forgiving viewer to completely overlook how profoundly familiar this material is, not only due to its echoes of Careny's earlier work. The relationship between Conor and Raphina - who, astonishingly, turns out to have secret heartbreak that her good looks and enormous surface-level confidence paper over - is not fresh in any way, and I don't know that either of the actors are up to the challenge of bringing something new to the material. If we might borrow the film's own milieu, this is like a cover song that skillfully recreates a perfectly fine original. And even then, one must deal with how limited of a character Raphina is: while Carney shades some darkness into her through some casual lines with bone-chilling implications, she's still pretty much entirely an inert fantasy girl.

Better by far are the scenes that deal entirely with the band; and even here, the film has to cope with the recent model of the Swedish film We Are the Best!, which covers a lot of the same material, better. Still, the loose, easy chemistry between the band members is hugely appealing, and in the form of miniature entrepreneur Darren (Ben Carolan), the film scores a really first-class precocious child character and performance. Certainly best of all is the scenes with Conor's family, including parents who are quietly warring with each other constantly and an elder brother, Brendan (Jack Reynor), who is a remarkable achievement in sketching out a rich and complex character in not many scenes. The film has a dedication to brothers everywhere at the end, which tips its hat that secretly, Brendan has been the secret heart of the movie all along: he is the animating force pushing Conor forward, and his tragedy, expressed phenomenally well by Reynor in a terrific monologue, feels deeper and sadder and truer than anything else in the movie.

A whole movie just about the Lalor family might be a real masterpiece; between them, Reynor and Aidan Gillen (wonderful as the family's bossy ass of a dad, sketching in backstory for several characters all at once just in the way he uses his voice and angles his body towards the other actors) are the two most impressive actors, and the family scenes are sharply focused in ways that the dreamy music-making sequences aren't - probably by design, but the precision and detail and subtlety with which the struggles and antagonisms of the Lalors are depicted is missed elsewhere in the film. It's cozily shaggy, frequently not to its benefit: the editing in particular is something of a minor-scale disaster. It's all in service to the performances, of course, but the ragged, obviously improvised way that scenes are cobbled together is clumsy and annoying; close-ups cutting to other close-ups of the same actor, or bobbing around looking at nothing in particular while waiting for songs to run out. I do not recall either Once or Begin Again feeling quite so sloppy in their cutting, and yes, this is how Carney gets to the casual, relaxed tone that makes Sing Street work, but it put me on edge anyway.

That being said, the film practically takes as its subject a certain desire to be forgiving to messiness when it is earnest. Sing Street is hardly great, but it is immensely likable and kind, even when challenging its characters a bit might be appropriate (especially during the ludicrous, fairy tale ending). It is a film that makes you feel very nice while watching it; not, maybe, the highest achievement of art, but hardly unworthy, and it takes its own kind of skill to make material like this feel as organic and realistic as Carney manages so easily, from start to finish.