The thing about Batman is that it doesn't really matter who portrays him. Most of the time, his face is under a mask, and his voice is modulated. Seriously, how many of you actually pictured Bale when you saw Batman? I imagine not many, because in the movies, Batman is all about the suit, the action and to some extent his voice during dialogues.
Plus, I doubt that Ben would need to give a strong portrayal of Bruce Wayne when compared to the Dark Knight trilogy. As much as it was about Bruce and his character, I believe that this movie is gonna be about Batman and not Bruce Wayne. So I don't really get what the hullabaloo is about. Calm the fuck down and judge him once the movie is out!