Overall a great movie except for one major complaint that I had, although I realize I'm in the minority view here. The ending is just silly. There is no way Rocky would have gone out the way he did, pretending to be a coward--he would have died as he had lived--with courage and composure--however he might agree with Father Connolly about how he had lived his life.
A better ending would have been for the father to have visited Rocky earlier. When Father Connolly arrives, he only has ten minutes to talk to Rocky before his execution. Had he arrived earlier, he could then have persuaded Rocky to write a letter to the "dead-end kids" gang who looked up to him that although he intended to die bravely, as he had lived--his life as a gangster was ultimately a failure and that he wanted the kids to know that and not make the same mistakes he did. They could even have published the letter in the paper, where it would have had equally dramatic an effect as the newspaper reports of Rocky's feigned cowardice during the electrocution scene.
Had they done the ending like this, Rocky would still have redeemed himself in the end, it would have made far more sense, and I think it would have made for a much better ending.