I have all the faith in the world for Ledger. Honestly, Nolan saw something in him for his take on the character. I loved Bale's and Nolan's words on his commitment to the role. Being talented but at the same time "fearless." You can't do something unless you devote your full attention toward it. Things only make sense when you force them to. He isn't the first choice for the role to A LOT of people, trust me. But if you put it in perspective, if he DOES succeed with the role, and everyone is pleased with his performance, those same people will praise him for it. It's guaranteed.