The trouble with radio, the instantness of it - too many politicians make themselves twits.

Instantness... I assume he means immediacy?

The good thing about Twitter, as opposed to, say, a live interview on the radio, is that you can think about a tweet before you make it, without anyone really noticing. This is true of all the non-voice, non-video means of communication available on the net (unless I am missing something which forces you to write before you are ready?). Indeed, the fact it allows for considered communication is what places it far and away above the old media (including f2f) in my view.

And it was nice of David Cameron to illustrate that point so, ahem, eloquently.