I haven't checked any reaction to the debate on Twitter, email, TV commentary, or other things of the sort. Watched this just now with my wife, while more or less off the plane from China, and this is the raw first-impression dump.
As a matter of performance, this was as one-sided a win for Obama as the first debate was a one-sided embarrassment for him. Romney's ill-at-easeness on nearly every subject that came up was palpable, as was Obama's barely-contained certainty on all these issues (which burbled out mainly with the "we have these ships that go under the sea, called submarines" line).
As a matter of substance, it was depressing in principle that this was the level of presidential-campaign discussion on China, India (nothing, or close to it), climate change and the environment (nothing I heard), energy (next to nothing), Europe (ditto).
But it was more striking as a matter of substance that on virtually no issue did Romney make an actual criticism, of any sort, of Obama's policy or record. Including topics where he used to disagree, like the timeline for withdrawal for Afghanistan! Instead it was, "I agree, but you should have done it better."
I have no idea whether anyone was still watching at this point. I have no idea how much these last-of-three debates matter. I have less idea why Obama let himself do what he did the first time around, or why Romney was not better primed for this one. But I know that Obama did very well this evening, and Romney put up his worst showing.
The debates are now behind us. Two weeks to go.