I think they're both very talented actors, but very different. Peter Dinklage plays Ghost like a leading man, testosterone uninhibited, cynical and sarcastic. Based on interviews, he was kind of just being himself, not caring too much about what you thought. Nolan North, on the other hand, is playing Ghost like a mild-mannered sidekick, geeky, polite and self-effacing. And this is the guy who played Nathan Drake -- this actor can do [i]a lot[/i] of different voices, and he/they chose this one. I think he sounds like Otacon from Metal Gear Solid -- the archetypal helper. I believe both gave it their best. Yes, even Peter Dinklage. He can't help that his natural speaking voice sounds more monotone, or 'bored,' than others. I sincerely think everything was on purpose as a creative decision. I don't believe anybody 'phoned it in.' All actors just have very different minds, and directors change their minds too.