A friend of mine said it looked like "Funny Taxi Driver." Judging from the trailer, it looks better than I expected. Better than it should be. Like Travis Bickle, it seems that they're going with the story of a man, already on the edge, that snaps after one bad day too many.
Like others have said, this origin story doesn't lock him down anymore than Jack Nicholson's origin story of the character. As Walt Whitman said "Do I contradict myself? Very well, then I contradict myself, I am large, I contain multitudes."