Let me stress the point that I have never been one to criticize a director for being self-indulgent. In fact, I find it to be, without exception, a strongly positive trait of any director's work. Even disappointments like "Snake Eyes" were still relatively interesting to watch, because De Palma has a way of filming his pictures that could make the most uninteresting story seem riveting. I will not use De Palma's tendencies toward caricatures and camera trickery against him like other critics. These things are the reasons that I have liked De Palma in the past, and also the reasons why I still look forward to his work even after years of disappointment.
I have not mentioned his current film thus far, because I am not sure just how it fits into his repertoire, or even how it fits into my brain. I don't know if "The Black Dahlia" is any better or any worse than De Palma's previous work, and I suppose I really don't care.
I am recommending "The Black Dahlia" because I miss the bravado. I like the time era and the subject matter, and I also (once in a while) enjoy a plot that careens out of control and comprehensibility to the point where the viewer is just happy that everything worked out okay, regardless of how the characters got there. I don't mind that the movie had very little to do with the Black Dahlia mystery itself, because it had a lot of other things going on. It's more the fault of the production companies that advertised the murder as being the plot, than it is De Palma's for not making it so. I suppose I liked "The Black Dahlia", admittedly because I wanted to like it, and it didn't do anything to betray that want.
I should mention that if it weren't for the effort given to Aaron Eckhart's character, I don't think I give this movie a passing grade. Eckhart, like Tim Roth and Johnny Depp, has the ability to forge so much history and infuse his characters with such depth, that they can overcome plot holes and sparse development. I will go to a movie just because Aaron Eckhart is in it, and I can't say that for many actors.

"The Black Dahlia"