I think in some respects Catwoman wasn't an essential character to the plot, obviously she was nice to look at and had some fun action scenes but I didn't feel that her own 'need for redemption' subplot really evolved beyond the fact we knew she wanted better for herself, like many other subplots it sort of vanished, then at the end we saw her with Bruce and we're left to assume that she's found what she was looking for.
I was wondering when Bruce may have jumped ship too. The bomb having 2 mins left on the timer means it must have been travelling pretty fast out of the city to get the 6 miles away or whatever it was, I guess that also means it has to have got 6 miles away from where Bruce was depending on when exactly he did jump ship. I'm not too bothered though, and I guess it is set up to make it seem like a surprise when he survives.
I wonder whether he'd be allowed to kill Batman, if the studio wants to make more films then it's better that he lives, unless they want to recast or have 'Robin' take over.