"Interesting pick." And that's all he says before the Doctor starts playing again.

The meaning is muddled through the guitar. It's not the instrument that the song was originally written for, after all. But the otherworldliness shines through anyway. The song doesn't seem to pay attention to conventional musical theory, jumping around through various harsh chords. It's beautiful and unearthly but there's something a little sad underneath it.

And not even two minutes after he's started, the Doctor just stops. There we go, song's over. "What'd you think?"