I do not think, as some other people do, that Capaldi is too old to play the Doctor. William Hartnel, the first Doctor was 55 years old when he started the show, which is the same age as Capaldi is now. Age has nothing to do with performance. I think he'll be brilliant.
My hesitation is that he may turn out to be a dark Doctor. During the 2012 Christmas Special, Matt Smith's Doctor was quiet and brooding because he'd just lost his two companions. Understandable, but if I may quote Strax, "I am opposed to your current apathy." I didn't like the do-nothing Doctor. If Capaldi's Doctor turns dark, it makes me wonder what would cause this.
The greatest concern I have is that Jenna Coleman may be leaving the show. If the Doctor loses another companion so soon, I could understand him becoming angry at the universe. As a writer, part of me wants to whip up a quick fan fiction about my what-ifs, but sorry, I have too much on my plate as it is.
I really don't know that much about Peter Capaldi other than his role in The Fires of Pompeii. I look forward to more information about the 50th Anniversary and the Christmas Specials. Never a dull moment as a Whovian.
