Anyway towards the bottom the writer makes a very quick and useful analysis of the episode now in the light of The Night of the Doctor and how as I supposed with whimsy and Tenth, you could see the Ninth Doctor's arc as much now about learning what it is to be the Doctor after setting that identity aside for an incarnation. It also makes sense of an exchange in The End of the World:
ROSE: Who are you, then, Doctor? What are you called? What sort of alien are you?The subtext of that line has always confused me. It is identity related but never quite made sense in context. Now it sounds like the Doctor trying convince himself of who he is as much as Rose, as though he has to keep reminding himself that he's the Doctor again and about what that implies. Retcons are good aren't they?
DOCTOR: I'm just the Doctor.
ROSE: From what planet?
DOCTOR: Well, it's not as if you'll know where it is!
ROSE: Where are you from?
DOCTOR: What does it matter?
ROSE: Tell me who you are!
DOCTOR: This is who I am, right here, right now, all right? All that counts is here and now, and this is me.
ROSE: Yeah, and I'm here too because you brought me here, so just tell me.
COMPUTER: Earth Death in twenty minutes. Earth Death in twenty minutes.