Aftermath:

Benedict Brogan (Telegraph): Debate verdict: Brown scrabbles to survive, Cameron stays calm and Clegg gets the cream

Guidofawkes (Blogger): Quote of the Day: David Laws said... "There were low expectations for Gordon Brown and he failed to live up to them...

Johnprescott (Still deluded): Substance beats style EVERY time. Solid win for Gordon! 

Vital Statistics:  

36,483 people tweeted 184,396 tweets (three times the number tweeted during Nick Griffin's appearance on Question Time), at a rate of 39 tweets per second, amounting to 5.4 per cent of all tweets at the time. Peak of 9.9 million TV viewers, averaging 9.4 million (less than the Doctor Who episode the week before and about half of the last X Factor Final's viewing figures).

Verdict: 

More than 250 times more people watched the debate than tweeted about it, and considering that the people tweeting were tweeting about old media anyway, it has to be the winner. But if you want to be cheesy about it, than the winner was, in fact, the electorate.