I think it's a nice commercial. It does a nice job of pointing out some of the negative stuff said about him is ridiculous. He gave up money and perhaps shrunk some of his legacy to win and play with friends.
I said a long time ago that this story, handled correctly, would have been a huge PR win for LeBron. Ultimately, we always complain that stars are selfish and don't care about winning. Yet when a guy takes less money and is willing to sacrifice personal legacy we want to jump on him?
The story should have been great, but the path he took to get there derailed that along the way, and now through the power of Nike, he'll slowly begin the campaign to make people forget about that path and remember the destination.
It will be interesting to see how much his image softens, I'd guess that within a year the majority of fans who care about his path to the Heat will soften their stance on him. However, ultimately, he hit the nail on the head in his first question.
Do I think you should admit you made mistakes? Yes.
If you really want to rehabilitate your image, then that's what you should do. Generally, in this country, people will forgive anything if you say you're sorry. Do steroids and apologize? Cool. Do steroids and act like it never happened even with conclusive evidence against you? You will be hated until apologizing.
Really, it's that simple. The best thing LeBron could do to rehabilitate his image is just to say to a beat reporter at any point, "In retorspect, the 'decision' wasn't a good idea. I was happy to raise money for the boys and girls club, but it was awfully insensitive to the fans of Cleveland, and I wish I had done things differently". People would then move on within a week.
Anyway, the commercial certainly seems to attempt to rehabilitate his image, and it does a solid job given he's not going to apologize via a Nike ad so contrition wasn't really an option. Here's how ingenious Nike is though, LeBron plays the "unfairly persecuted", "I don't care what you think", and "buy my shoes because you like me" cards all at the same time. That's some talent.