In an interview with The Hollywood Reporter Sir Ian says,
“It was a little like going back to something that wasn’t necessarily going to be particularly challenging, Gandalf is still inside me, as it were, so the business of getting to know a new character — I was sort of going to be robbed of that.”
But he thought differently once a friend asked him how he could explain quitting the role to all of the fans.
“You felt, how many millions of people are waiting for it?” he says. “They wouldn’t understand if you weren’t as keen as they were.”
And it is Gandalf the Grey he is playing, not the more serious Gandalf the White. Sir Ian says,
“Peter Jackson and I much prefer Gandalf the Grey, who was a man who did manage to enjoy himself,”
We’re all looking forward to seeing that twinkle in Gandalf”s eye in The Hobbit: An Unexpected Journey when it’s released this December.