If one had only listened to the debate rather than watched then I suspect the score would be pretty even, however even is not enough to get Clark over the line.
The telling part was the contrasting demeanour of the two; Clark looked tired and haggard whereas Key looked pretty relaxed and confident.
In short we saw a Prime Minister on the way out and a Prime Minister on the way in so I would have to give the result to John Key.
One interesting snippet during the analysis afterwards was Linda Clark's observation that the National Party's private polling showed it's lead extending.
Another point; John Campbell will have a sore throat on Tuesday given the amount of talking he indulged in.