[Jeritron]

He did change his voice. However he didn't change it as much. That's the difference. Bale really altered his, whereas Keatons is just more quiet and hides emotion. I like them both.
Theres always the arguments about who's better Keaton or Bale. I don't see why it matters. I'm glad we've had both.
Keaton was excellent. Complains about how he played Bruce Wayne are not founded because thats the screenwriters, not him. He played what he was told to play excellently, and thats a shy quirky billionaire.
As Batman, he acted great, he just didn't ask much. Once again, not his fault he didn't write the script.
His size and chin isn't his fault, he did a great job regardless. He wasn't THAT small, and he did have great manerisms and acting in that 200lb suit. He also had perfect eyes, mouth and voice.

Bale was excellent as well. He really embodied the Bruce Wayne side better. However the script went more into his character and gave him more time. He had more of a chance to play the "correct" Wayne/Batman. He also had material in his role that fans are more fond of.
I like Bale as playboy Wayne. The only complaint is that at times his acting is wooden and fake. And it's at times when it shouldn't be. Sometimes he slips into the American Psycho role, and talks that way. Which sucks. Especially when he talks to Rachel. He's a great actor and a great Wayne/Batman, but he lacks real emotion.