I feel like this is 10’s most important line, concerning Rose, at least. I think this because throughout the episode, Rose is trying to believe this new man could be her Doctor. He saves the day, but underneath it all, there’s still something missing. She had to admit she likes him, but she doesn’t know if he’s really The Doctor. And then he says it. Fantastic. A word her Doctor used over and over again, and she realizes…
It truly is him.
Mickey, my love, you are underappreciated.