Dark Victory is a direct sequel to The Long Halloween. To be honest, I didn't feel as it was very necessary. The story is practically the same as The Long Halloween but instead of leaving totems to represent the holidays, the killer leaves hangman notes.
The execution is practically the same as in its predecessor. There are several suspects and Batman and the police go from suspect to suspect, never being sure who the real culprit is. One by one, the most known villains in the Batman universe appear to create a distraction in the investigation and there is no significant development or backstory to any of them.
When it comes to the characters, Dent continues to be very interesting. We see the changes in his personality after becoming Two-Face and how he stills struggles with the idea of right and wrong. In this comic, Robin is introduced but I wasn't happy with it. His introduction seemed rushed, with not much time used to develop his story arc. I liked how they tried to draw a parallel to young Bruce, though. Gordon becomes more of a minor character. He doesn't do much to push the investigation forward, which bothered me a lot. He fades into the background and is forgettable.
I was a bit disappointed with this comic. I wished there was more time devoted to Robin's story, since it was his introduction. But it made me want to learn more about him as well as Catwoman.