Best: Got some of his mojo back. Several answers especially on twin vulnerabilities of Iraq and immigration channeled his genuine views and transcended mere debate prep. Sold bipartisanship, hard choices, fiscal discipline, anti-torture, and experience all his aces.
Worst: Pushback against Romney's attacks on his support for biparitsan immigration and campaign finance bills summoned up the peevish ghosts of campaign 2000. Speaking of 2000: planted seeds of a new Confederate flag problem with another evasive answer that he (probably) doesn't believe.
Next Rudy Giuliani