It's hard to believe how Keaton can go from Beetlejuice, to Batman. But he does it, and he does it extremely well. He's the most believeable Batman by far, because like Burton said in an interview; "I couldnt see many people putting on a bat costume, but I could see Keaton putting on one!"
His range is unbelieveable. And I think hes a very much underappreciated actor in hollywood. His presence will definately be missed in the future Batman films.