Might not be that bad.
At first I was angered by the fact they were doing this, but I am not now. After I read the Jake La Motta book, he has had an interesting life that Scorsese's flick didnt pick up, so I do believe that this film could actually be great, and I can't wait for it. If they pick the right actor to play Jake, it could be outstanding, although I don't it will surpass the original Raging Bull. Just give it a chance.
I also recommend anyone skeptical on the film to read La Motta's book.