Like almost everyone else (I assume) who saw the debate, I thought Obama was flat and off-balance for most of the night. His answers were usually correct if lacking in conviction the first time through. But he frequently made the mistake of doubling back and undercutting himself--the kind of thing people do when they're exhausted.
On the dubious capital gains tax question, for example, Obama's first impulse was basically sound--he suggested that, if a lot of rich hedge fund managers are going to re-classify income as capital gains to exploit the lower tax rate, then, as a matter of fairness, it makes sense to raise that rate a bit. (Simply prohibiting the re-classification would be a more precise way to serve the same ideal, but let's not quibble...) The problem was that Obama got tangled up on unrelated issues like the mortgage crisis as he kept talking--and as Charlie Gibson kept insisting (incorrectly) that cutting capitals gains taxes raises revenue. He should have quit while he was ahead.
By contrast, Clinton was generally on her game. She seemed energetic and answered authoritatively if a little glibly at times. (Obama was right to point out, for example, that she's trying to have it both ways by accusing him of raising taxes to shore up Social Security, while at the same time suggesting she'd have a 1983-style commission study the problem--the kind of group that's very likely to recommend his proposed lifting of the payroll tax cap.)
But, obviously, the real story of the night was the crazy gauntlet of questioning ABC put Obama through. The first half of the debate felt like a 45-minute negative ad, reprising the most chewed over anti-Obama allegations (bittergate, Jeremiah Wright, patriotism) and even some relatively obscure ones (his vague association with former Weatherman radical Bill Ayers).
My immediate reaction is that there's a huge double-standard at work here, but not the one you'd think. That is, it's not that Hillary didn't get her fair share of tough questions tonight (she didn't, but there have been plenty of debates where she's been ambushed and Obama's gotten off easy). It's that, when Hillary gets mauled by moderators and opponents, voters generally feel sympathetic to her. Most people--even the skeptics--feel like they know her, and we don't like seeing people we know treated unfairly. But when Obama gets ambushed, I think the effect is more damaging. He doesn't have the same longstanding relationship with voters. And when you hear unremittingly negative things about someone before you've fully formed an opinion, it tends to affect how you see them.
Having said that, what kept this from being a disastrous night for Obama is that Hillary couldn't leave well enough alone. She looked classless in slapping Obama over Ayers after the moderators had kicked him in the teeth for 30 minutes. And Obama shrewdly underscored this impression with his gracious refusal to pile on over her Bosnia-embellishment flap.
So, all in all, a huge missed opportunity for Hillary. I think she'll gain marginally if at all. She may have lost as many people as Obama did from all the incoming he took.