Answer by taking a quote from the following article:

Once is a 2007 Irish romantic musical drama film written and directed by John Carney. The film stars Glen Hansard and Marketa Irglova as two struggling musicians in Dublin, Ireland. Hansard and Irglova had previously performed music as the Swell Season, and composed and performed the film's original songs. Once spent years in development with the Irish Film Board and was made for a budget of EUR112,000.

Once was met with extremely positive reviews from critics. Upon its March 2007 release in Ireland, RTE's Caroline Hennessy gave the film 4 out of 5 stars and termed it "an unexpected treasure". About the acting, this Irish reviewer commented, "Once has wonderfully natural performances from the two leads. Although musicians first and actors second, they acquit themselves well in both areas. Irglova, a largely unknown quantity alongside the well-known and either loved or loathed Hansard, is luminous." Michael Dwyer of The Irish Times gave the film the same rating, calling it "irresistibly appealing" and noting that "Carney makes the point - without ever labouring it - that his protagonists are living in a changing city where the economic boom has passed them by. His keen eye for authentic locations is ... evident".  In May, on Ebert & Roeper, both Richard Roeper and guest critic Michael Phillips of the Chicago Tribune gave enthusiastic reviews. Phillips called it, "the most charming thing I've seen all year", "the Brief Encounter for the 21st century", his favorite music film since 1984's Stop Making Sense and said, "It may well be the best music film of our generation". Roeper referred to the film's recording studio scene as "more inspirational and uplifting than almost any number of Dreamgirls or Chicago or any of those multi-zillion dollar musical showstopping films. In its own way, it will blow you away." Once won very high marks from U.S. critics; it is rated 97% "fresh" by the film review aggregation site Rotten Tomatoes and scored a grade of 88 ("universal acclaim") according to Metacritic.  In late 2007, Amy Simmons of Time Out London wrote, "Carney's highly charged, urban mise-en-scene with its blinking street lamps, vacant shops and dishevelled bed-sits provides ample poetic backdrop for the film's lengthy tracking shots, epitomised in a sequence where the Girl walks to the corner shop in pyjamas and slippers while listening to one of the Guy's songs on her personal stereo. With outstanding performances from Hansard and new-comer Irglova, Carney has created a sublime, visual album of unassuming and self-assured eloquence." The Telegraph's Sukhdev Sandhu said, "Not since Before Sunset has a romantic film managed to be as touching, funny or as hard to forget as Once. Like Before Sunset, it never outstays its welcome, climaxing on a note of rare charm and unexpectedness."  The film appeared on many North American critics' top ten lists of the best films of 2007:  In 2008, the film placed third on Entertainment Weekly's "25 Best Romantic Movies of the Past 25 Years".

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The film appeared on many North American critics' top ten lists of the best films of 2007: