Deb and I saw the film on Johnny Cash last evening http://www.walkthelinethemovie.com/. From our perspective we found it moving and realistic. The actors who portrayed Johnny and June seemed to me to hit homeruns. Hollywood left out a clear conversion to Christ which I believe, both Johnny and June Carter Cash professed. Here is a page about Johnny's life. Especially helpful is the information from wikipedia: http://www.answers.com/topic/johnny-cash
I remember watching Johnny on a Billy Graham telecast. My memory tells me that he talked (as only he could) about God's grace, the cross and forgiveness of sins, his sins. I think he and June were friends with the Grahams. Recently on "Jesus Creed" we had an interesting conversation about and surrounding this movie: http://www.jesuscreed.org/?p=590 We know of someone who was turned off years ago because Johnny Cash did a concert in their city, drunk.
This movie, for those of us who know "the rest of the story" is a powerful witness of God's grace in the lives of those in the margins who often fall between the cracks. It was one of those movies that I was glad to have seen and will not forget.