I predict the following. Obama backers will think Obama won (maybe "wiped the floor with him"), and McCain floundered. McCain backers will think McCain won (maybe "wiped the floor with him"), and Obama floundered. Some will say it "made their mind up", and others will say they're undecided. If you were already backing one candidate, you thought he did really good (but for a small % who don't want to come off being bias who will say it was a draw, or the other guy made good valid points). And tomorrow, we'll go back to the same old arguments.
I'm interested to see how much of the "foreign policy" debate is actually discussing the economy. The more the economy is discussed, the better it is for Obama.