I really don't like "town hall meeting" debates. First, they are (in this context) populist gimmicks to test a skill that has nothing to do with being president. Second, this was not a town hall meeting at all, but a scripted event with bad questions that the candidates had no choice but to evade.
Having said that, I was surprised at how awkward and inarticulate McCain often was in a format that he claims to especially like and that he tried to induce Obama to join frequently over the summer. McCain was not embarrassing, and he had some good moments--as well as an interesting, but probably unworkable, proposal to have the Treasury buy up bad mortgages. But his body language and demeanor were mostly terrible, while Obama seemed fluid, comfortable, and--something that has not always been the case--charming.
The substance of the debate had no surprises and didn't vary much from the first debate. Given that all the polls, and the subsequent momentum, gave Obama the edge after the first debate, it's pretty surprising that McCain said almost nothing that he hadn't said earlier. Obama had no big new ideas either, but he's not the one who has to turn the campaign around.
I think the big advantage Obama has coming out of the debate is that he was more likable than he usually is--and that will make it much more difficult for the attack ads and the Palin barbs to turn things around.
I saw nothing tonight that seems likely to change the current trajectory of the campaign. And that, of course, is good news for Obama.