Struck me that, when it comes to making a winning speech, which manages to be non-grandiose and inspirational at the same time, he's up there with Tony Blair in the early days. Mind that's a two-edged compliment.
I can't see where lack of experience really comes into it. After all, Bush had what on paper looks like quite a lot of relevant experience, and look what you got there? And if he's on the right of his party, isn't that going to apply to any candidate selected by the Democrats?
His big problem is he looks about 12. Plus, I imagine there are still a fair number of voters who would always find some reason not to vote for a "black" man.