Batman was not loyal to the characters much. Instead it developed and ADAPTED the story. I see it as a fan fic, in that it strays a lot from the continuity and character of the comics (ie Batman has guns on his Batmobile and kills people). But its a bloody awesome fan fic at that.
Forget the comics for just ONE second, and put aside all of the fanboy inhibitions, and view it as a MOVIE. That's what I do.
Batman and Batman Returns are absolutely brilliant movies in their own right. Anyone that doesn't notice the character development is a zealot.
There's plenty of room for Tim Burtons Batman, Bob Kane's Batman, the 60's TV Show Batman, the Animated Batman.
Batman, in the comics alone, has gone through many changes in his character. For people to say Batman is a crap film because it betrays the comic, because he kills criminals, is full of crap. Batman used to carry a gun, of all things, during one comic stint. He has gone through many, many changes in the comic books so how CAN a movie of such a mess of a comic, cater for everyone?
Batman is a character that has been constantly changed. He isn't like Spider-Man where the characters have stayed intact since they began. Batmans been all over the place so the movies can interpret that how they damn well like, to be fair.