You know, classically Batman was not some kind of ultimate superior ninja fighter nor do I think too many people would enjoy that because that angle TAKES a lot FROM the character.
Seriously, it is relatively recently in the comic book development that necessitated Batman being the supreme master of 10 trillion martial art styles and being able to beat every athlete on all the Earth who was not super-humanly enhanced in their associated sports hands-down.
The reason for this is that Batman is meant to be HUMAN and, moreover, it is god damn awful writing to claim that one guy, no matter how stinking unbelievably rich, no matter how traumatic his parents death, no matter how dedicated... could possibly out-perform and outdo thousands of people's lifetime dedications in a matter of less than a decade.
Okay, so he trained with Ra Ahl Gul and the league of assassins, granted, but only for a relatively SHORT time. And, yes, I know there is this whole white power mentality that all white people can do all Asian stuff a hundred million times better than any Asian could possibly do it, but well... its been done to death in Chuck Norris and Steven Seagal films and the recent Matrix and Kill Bill films and so until we get a Green Hornet film so we can put the rich playboy gun-fighter detective part and the car-racing ninja part into two different characters of more appropriate ethnicities can we please leave that **** in the proverbal mental closet?
And until we necessitate Batman hanging out with and standing toe-to-toe with Superman, Green Lantern and the modern Superman-esque Wonder Woman, we don't need whatsoever for him to be some kind of ultimate pinacle super-human.
The fights in Dark Knight are exactly what one would expect from someone of Batman's reasonably acceptable skill level loaded with the displayed gear. It is hard, grissled and realistic just like the rest of the film. Yes, maybe it would have been nice if we could have seen some more like Batman Begins where he APPEARS to be a better fighter because the camera isn't focused so much on him as much on the criminal, but he was shown getting hurt, out manuevered and beaten at times to maintain the humanity of the character.
For all his riches, all his technology, all his brooding and secrets, ultimately Batman is just a guy dressed up in a silly costume that is meant to make him APPEAR to be more than human. That's the draw of the character, he is feasably achievable for a human. It does not call for being born on an alien planet, doused with radiation in some manner, being injected with some sort of drug, making deals with demons, being born half-vampire or loading up with a ridiculous arsenal of guns and mowing people down mercilessly... all one needs to do in order to be like Batman (or most of his villains for that matter-- Freeze, Bane and Poison Ivy being the obvious exceptions) is have dedication.