No clear "winner".
Obama was better on style and demeanor.
McCain was better, especially on the second half, on "points", but Obama was toe-to-toe with him most of the way, and refused to let McCain’s spun "facts" go unanswered. In a debate largely about foreign policy — McCain’s bailiwick — that might actually be a "win" for Obama. In fact, McCain’s taunts that Obama "didn’t understand" or was "naive" seemed to fall flat.
Some early polling of undecidedsfrom CBS News:
40% of uncommitted voters who watched the debate tonight thought Barack Obama was the winner. 22% thought John McCain won. 38% saw it as a draw.
68% of these voters think Obama would make the right decision about the economy. 41% think McCain would.
49% of these voters think Obama would make the right decisions about Iraq. 55% think McCain would.
UPDATE: Ezra Klein writes: