Fans of The Commitments will raise a glass of Guinness to this sweet, modern-day Irish version of those let's-put-on-a-show movie musicals of the 1940s. A street-level story of a 30-ish singer-songwriter (Glen Hansard of the Irish rock band The Frames, who in fact appeared in The Commitments) and his chaste romance with a young Czech immigrant cleaning lady/pianist (Prague-based singer-songwriter Marketa Irglova), Once is a far less glossy Music and Lyrics with a melancholy vibe. In fact, it's an actual backstage musical, the kind with songs integrated into scenes of street busking, recording sessions, rehearsals and such.

As in The Fantasticks, the two main characters are credited only as "Guy" and "Girl." There doesn't seem much need for that affectation, but that's really the only thing that seems affected in a movie so naturalistic it's like it was deliberately photographed with a surveillance-camera clunky graininess to evoke reality-show footage. The guy plays guitar for spare change on Dublin's Grafton Street, where despite the trendy shops, the tips are slim. One evening after he's played a particularly haunting song, an inquisitive young woman dressed like a scrubbed-up urchin brightly interrogates him about what girl broke his heart so much that he wrote a song about her.

The guy's a little taken aback but can't get rid of the apparent stalker even after confessing that his day job is fixing vacuum cleaners. "Great!" she responds--she has a broken vacuum cleaner! Over the next couple of days, she brings him the busted Hoover, they retreat to his dad's repair shop, and he learns that when she's not selling tsochkes on the street, she's a classically trained pianist who plays for an hour a day. She's too broke for a piano, but a kindly music-store owner lets her use the shop's while he's closed for lunch. (Ah, gotta love that leisurely European workday!) She also has a two-year-old daughter and lives with her mom in an iffy immigrant flat.

To writer-director Carney's credit, none of this reeks of meet-cute. Instead there's that tentative, awkward, maybe-maybe-maybe sense of Is-this-the-one?-ness. Seemingly semi-improvised, the movie evokes real falling-in-love with an authenticity that your average studio romantic drama feels too slick and removed to have. Complications steer the romance like a bicycle through James Joyce streets.

The naturalism goes overboard at one point, when the girl listens to one of his songs on a homemade DVD and whisper-sings along badly, despite Irglova being a marvelous singer elsewhere in the film. There's also the inevitable studio-recording montage, in which the seen-it-all producer eventually starts to really listen and realizes dat dese kids, dey got sumpin'! Compounding this is a silly Frisbee beach montage afterward. But outside of that jolting foray into "The Monkees," Once is twice-blessed: good songs, and a real story--not just a clothesline on which the tunes can hang.