Great performances, good music, mediocre story. Joaquin Phoenix is a credible as Johnny Cash. Unfortunately, Mr. Cash marched a very self-indulgent path in life, thus his film suffers. The story arc is not the only problem. Much blame rests with the release date.
Timing plays a big role in the audience perceptions. When two thematically similar movies hit the market within a short time span, if both are of comparable quality, often the last one out fizzles. A recent example of the first time home run, second time ground ball effect: Cinderella Man. A solid, well-written and executed story, the Depression era boxing docudrama chased the heels of Million Dollar Baby. Audiences had their fill of boxing and the story of Maggie Fitzgerald and Cinderella Man underperformed. Last year Ray, the story of Ray Charles, stormed the theaters, leaving Walk the Line stale popcorn. Had I not seen Ray, I would have enjoyed Walk the Line a bit more.
Verdict: Worth a look. DVD rental.