So the idea that a bunch of DC comics writers and Japanese anime artists collaborating to make Batman sounds neat...on paper. In practice what it means is that you end up with something similar to 2 out of 6 segments having awesome animation; 3 out of 6 segments having awesome writing and only 1 out of 6 segments having both. I think one of the things that hampered this was the idea that they were tying it in to the Dark Knight universe from Batman Begins (ie the highly popular movies) setting the story between them. They were obviously trying to go for something similar in scope to the Animatrix, but the thing is with the animatrix, the artists (I think) wrote their own scripts as well. I mean, had the anime people been able to take their own twist on Batman (as the whole video was originally marketed) I imagine that they would have been able to tell stories much more suited towards their animation style. I mean you could have had an homage to the 60's era Batman or the 90's cartoon or the Graphic Novel Dark Knight or even something wholly original. Instead they told a series of interlocking stories that could have been interesting but for the most part weren't.
The lesson from this is that one or two neat ideas might work in synergy...but three or four and you'd better wait to try it first with something simple before you take a huge leap into the abyss.