Musicals notoriously have a disposable plot that merely exists to connect the songs and production numbers. This Alan Jay Lerner-Frederick Loewe re-working of George Bernard Shaw’s Pygmalion is doubly unusual – not only does it have an intelligently coherent text underpinning it but the songs match Shaw in wit, both lyrically and musically. The only somewhat niggling issue is that whilst the songs are impressively well-integrated with the book this does not apply to Eliza's "I Could Have Danced All Night"..
With George Cukor’s polished direction, Cecil Beaton’s glorious costume and set design (the Ascot Race scene is the high-point in this respect) and Rex Harrison and Wilfred Hyde White as a couple of confirmed bachelors (whether Hepburn does justice to the role of Eliza a Covent Garden "guttersnipe" and Julie Andrews who played the part in the original stage production is a matter of some debate) My Fair Lady is indeed irresistibly charming although for all the unequivocal pleasures it provides it lacks that Tin Pan Alley swing and physical exuberance that marks Hollywood’s greatest musicals and feels overlong despite the fact that Freddy Eynsford-Hill does very little as Eliza's ardent suitor and Colonel Pickering simply disappears).
THe film was a huge box-office success. Beaton won an Oscar for costumes, Harry Stradling for cinematography (it was filmed in Super Panavision 70), Andre Previn for Score Adaptation, Beaton and Gene Allen for Art Direction, Rex Harrison for Best Actor, Cukor for Direction and the film won Best Picture. Somewhat ironically, because Hepburn's singing was largely dubbed by Marni Nixon (who had done the same for Natalie Wood in West Side Story in 1962), the actress was not nominated for Best Actress, the Oscar going to Julie Andrews for her role in Mary Poppins.
FYI: Harrison played the part in the 1956 Broadway production on which the film is based but Audrey Hepburn took the place of Julie Andrews who had played the role opposite him, a controversial decision on the part of Jack Warner who favoured Hepburn's box-office clout, despite the fact that at 35 she was playing a 19 year old Eliza. Adding to the sense of might-have-beens, for a while Peter O'Toole was in contention for the Higgins role as was Cary Grant.