It's going to be very easy to overpraise Once, and a little overhyping is a dangerous thing for a movie where much of the enjoyment comes from how low-key and scrappy this film is. So a little focus on some of the flaws is probably in order. Director John Carney, with a few films and television shows already under his belt, is decidedly amateurish in his direction here. The camera switches between handheld and static shots with no real underlying reason, and often floats around a scene to the point of distraction rather than giving a fly-on-the-wall impression. At several moments the background cast or secondary characters acknowledge the camera directly. Sometimes it's only a glance, at others it's a group of children staring and following the camera as the character goes about her scene. And the story? As simple, bare-bones as you can get, not even filling an entire 90 minute running time.
I mention the film's flaws not to denegrate the film, but actually as a strange little honor. It would be a disservice to not mention the various flaws of this film. Because somewhere along the way the films flaws become it's strengths, and the scrappy, rough-hewn look and feel mirror and magnify the story's emotional core. As in the film's inspirational musical numbers, where all of the disparate pieces come together. The guitar with holes worn in it, the borrowed piano, the strangers gathered at the last minute to play backup. The pieces are unspectacular, but as they come together the whole is more than the sum of it's parts, and the music and movie begin to soar as something more emotional and genuine than multiplex audiences can usually expect to find.