The main character, a folk singer who isn't necessarily an easy character to like, is obnoxious, self-centered and a bit of a loser. You know, he's a musician. Somehow, you like the character regardless of his flaws. Isaac plays him with humanity, as a sort of everyman with talent. Sure he is a jerk but aren't we all jerks sometime? As you see bits and pieces of the business he is trying to succeed in you begin to see where how the seeds of his attitude were sown. When he decides he wants out he seems trapped in a career that he loves and hates. It is a dilemma familiar to any small time musician.
While there are numerous characters in the film--and many of them are music archetypes--the only one the audience really gets to know in depth is Davis. In the movie Davis is given the chance to make up for his decisions, to atone for his sins. In most Hollywood films characters leap at this chance. Not here. It isn’t so easy here and it makes him more human. When there is an easy out, something to make an audience feel good? The Coens do not take that easy path.
No one in the film seems rotten to the core (with one or two exceptions) but there are not many angels either (with one or two exceptions). The people who seem decent may have had to sell their souls, or other bits and pieces, while the people who represent the worst in the music business may have more integrity than it seems.
The film leaves you with a feeling that while there is usually something dirty behind success, there is nothing noble in failure.