I must differ with a previous reviewer ---
"Even a subdued Hepburn seems to be more than a match for the men in this movie, although as portrayed in the film Schumann and Brahms are a pretty clueless pair."
I don't quite get that statement. "More than a match"? Schumann and Brahms are clueless about what? They all seem to have a wonderful time together.
"The audience ends up identifying with Liszt, who you get the feeling always knows how talented the lesser beings really are in this story."
That's a pretty pompous thing to say. Brahms and Schumann are the "lesser beings" to Liszt? That's like saying Beethoven was a lesser being to Mozart. What he may be responding to is Liszt as played by Henry Danielle, who is always masterful, whether playing his usual heel or, as here, a good guy.
He also refers to Song of Love as being "sanitized." That implies that there was something in the true story to be sanitized. I didn't think there was. I always thought of the Schumanns like the Brownings: love conquers paternal tyranny.
And as did the Brownings, so did the Schumanns help define an age - the Romantic Age. This is the era when artists were supposed to suffer for art or love. Schubert and Shelley were the icons. "Live for your art and die young!" If you weren't an artist, just plug in "love," like Rudolf at Mayerling. If one is aware of this context, then the film's melodrama becomes easier to accept.
Another issue I have with the other reviewer is his dismissal of how Hollywood treats history. I think if one did more research and less opinionating, they would find that the Hollywood of the studio system is conscientious about historical accuracy, unless one wishes to quibble. The major studios took pride in their products, and audiences of the time, unlike the dumbed-down ones of today, demanded and usually got an accurate rendering of history. Dramatic license is another matter, which one might debate, but one can make that debate for all scripts, whether for stage or screen.
One thing I agree about. Henry Danielle is always a treat to see, in particular when he plays sympathetically, against type, as he does here.
Finally, I believe Paul Henried has been unfairly neglected in the comments. Henried plays Schumann's torment perfectly. He is pitiable, yet possessed of a dignity and strength. Clarence Brown has chosen to have Schumann's progressive dementia caused by a kind of hideously loud tinnitus. I have tinnitus, and I can attest, that were it at the level depicted in the film, I'd have gone bonkers, too!
Schumann was very aware of his condition, and much of his music is a commentary on his descent into and occasional remission from madness. This plight, of being both victim and observer, is particularly poignant. Even more poignant is Clara and Brahms and Liszt, as well as Robert, helplessly watching the process, especially given their unsordid devotion to each other and to making beautiful music.
I see no bathos here, only a well-rendered, classic love story. I think if one has a problem with that, then one has a problem with the genre.