Coming late to this one, I can see Capaldi's Doctor being like the 6th. However, I think that the massive difference is that Peter is an infinitely better actor than Colin B. He even managed to infuse Malcolm Tucker with some humanity and pathos. So I think that he's much better equipped to play a character who's prima facie unsympathetic and unlikable and still have the audience root for him, without toning down the performance or playing for sympathy. I must admit though, seeing as he's best known for playing the abrasive and bilious Tucker, I had hoped that Capaldi's Doctor would be 'against type' and would see a gentler, more whimsical take on the character, without being as eccentric as Matt. Still, I'm sure he'll be great, whatever he does.