Moderator Martha Raddatz had perhaps the best debate, especially compared to the unfocused Jim Lehrer; she actually asked pointed questions and follow-ups.

And it was there that the campaign spin had to surrender to stats and facts. Ryan is a budget expert, but he either didn't want to acknowledge or didn't know his own campaign's proposal to increase military spending to 4% of GDP, adding $2 trillion in federal spending over 10 years and blowing a hole in their deficit reduction rhetoric. Likewise, questions about what specifically a Romney-Ryan administration would do differently about Syria, Iran or Afghanistan went essentially unanswered despite the flurry of words.

Joe Biden made his share of unforced errors -- interrupting Ryan far too much and getting so overheated at one point that he turned his frustration against the moderator in an awkward spate of finger-pointing.

Ryan also shined in his discussion of deficits and debts, contrasting the president's speeches with score-able policy. His closing statement was disarming and compelling.

The best moment in terms of style and substance was Raddatz's question about abortion and the candidates' shared Catholic faith. Both men gave serious, thoughtful answers on this most difficult of subjects -- but Ryan's anti-abortion agenda contrasted to Biden's belief that he could not impose his personal religious views on an individual woman's decision. It was an eloquent defense of the separation of church and state -- a core concept we have heard too little about in recent years.

This debate might not get as many viewers as the 70 million Americans who tuned in to the Biden-Palin debate in 2008 -- but it was far more substantive, energetic and serious. It was a great debate -- simultaneously civil and contentious -- the kind we need more of in the United States.

Biden's strong performance gave the Democrats a much needed shot in the arm, a compelling defense of their values and beliefs that will buoy their sagging morale and change the narrative going into the second presidential debate on Tuesday.

It might not have changed many undecided minds, but it changed the momentum -- and that's a win in our democracy circa 2012.

John Avlon is a senior political columnist for Newsweek and The Daily Beast. He is co-editor of the book "Deadline Artists: America's Greatest Newspaper Columns." He is a regular contributor to CNN's "Erin Burnett OutFront."

Julian Zelizer: Something for both sides

Vice President Joe Biden and Rep. Paul Ryan engaged in a vigorous debate, with a moderator who kept pushing the discussion along.

Both sides will find something in the debate that they can boast about. Ryan demonstrated he could debate policy areas where he is not as experienced, particularly foreign policy, and he handled himself well before the television cameras. He remained calm under fire. Ryan was also able to tell a few personal stories that he used to try to humanize the image of his running mate.

For Democrats, who needed a much bigger boost, Biden came through in that he was much more aggressive than Obama was in last week's debate, hammering away at Republican economic policies, warning voters about his opponent's Medicare plan and defending the administration's actions overseas. Biden consistently raised questions about whether Ryan and the Republicans are even telling the truth when they speak. During the last segment of the debate, Biden seemed to be at his strongest, a Democrat who was tough on national security and someone who was on firmer ground than his opponent with regard to understanding these challenges. Biden said what many Democrats wanted President Obama to say against Romney, showing the enthusiasm and the fire that was absent last week.

There are some viewers who might have been turned off by Biden's tendency to laugh and shake his head in dismissive fashion as Ryan was speaking. The danger for Democrats is that some swing voters read this as arrogance and partisanship rather than a sign of Biden's comfort before the cameras.

Like other vice presidential debates, this one probably won't have much of an impact on the electorate, though it will help curb some of the media discussion about Obama's poor first performance and generate some excitement among Democrats who were left deflated after Denver. Finally, both candidates handled themselves well enough that it probably won't have any major effect on their fortunes if they choose to run for the presidency in 2016.

Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" and of the new book "Governing America."

Aaron Carroll: Debate shed little light on Medicare, Medicaid

No one will confuse this debate and the last one. Both participants came prepared to fight. There are many who will say that Vice President Biden was too forceful, or was disrespectful, but for supporters of the president who wanted to see a more energetic response to the Republican campaign, Biden's performance was likely a balm.

The polls will tell us in the next few days, but if Biden's actions tonight inspire the base as I think they likely will, then the president will see some benefit.

Of course, my main interest is health policy, and in that respect, tonight was a bit disappointing. The entire discussion centered on Medicare. For all the bluster between the two campaigns, the differences between them on that program for the next decade are small.

For all the talk about the financial risk Medicare holds, neither wants to cut it severely soon. On Medicaid, however, the differences are stark; that program didn't come up at all.

I also was appalled that raising the Medicare age of eligibility was tossed off as an obvious thing to do. That's a terrible idea.

Dr. Aaron E. Carroll is an associate professor of pediatrics at the Indiana University School of Medicine and the director of the university's Center for Health Policy and Professionalism Research. He blogs about health policy at The Incidental Economist and tweets at @aaronecarroll.

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