Song of Love is the MGM-ified version of the lives and loves of 19th century musicians Clara Wieck Schumann (Katharine Hepburn), Robert Schumann (Paul Henreid) and Johannes Brahms (Robert Walker, who the previous year had played another composer, Jerome Kern, in Til the Clouds Roll By). Clara gives up her thriving career as a concert pianist to devote herself to her struggling composer husband Robert. Unable to cope with disappointment and failure, Robert dies in an asylum, leaving poor Clara to cope with seven children and mounting debts. At this point, the eminently successful Brahms, who has loved Clara all along, proposes to her, but Clara insists upon going it alone, perpetuating her husband's memory on the concert stage. Also represented in this musical "through the years" pageant is Franz Liszt, played with remarkable understatement by Henry Daniell. Clearly designed to capitalize on the popularity of Columbia's Chopin biopic A Song to Remember, Song of Love is slow and poky at times, though it's fascinating to see Katharine Hepburn at the piano (reportedly, she learned to play enough classical music to get by in the close-up scenes, though her music is dubbed in medium and long shots).
~ Hal Erickson, All Movie Guide