I'm honestly quite conflicted about Darker Than Black. While the overall premise is interesting and fairly unique, I found the first half of Season One utterly unremarkable. I did not manage to connect to the characters (partially because most of them are 'Contractors' who don't have any emotions are thus as vivacious as wet cardboard) and found the plot mildly entertaining at best. Funnily enough, while the series was mediocre, it was at least consistently so: I rated every episode a 7/10; none were particularly outstanding, neither in a positive nor in a negative way.
Thankfully, the second half of the first season finally turned into a consistent story, and the final quarter is truly outstanding. Why the rest of the season wasn't written in the same way, I'll never understand.
Season Two is a complete change of pace. The protagonist switches from a cold-hearted mercenary in his twenties to a preteen girl, yet becomes much darker in the process. Funnily enough, I found it much easier to emotionally connect to that preteen girl (perhaps because she had actual emotions), and the entire season features a consistent plot that advances with every episode. While not every episode is consistently fantastic, the second season of Darker Than Black is at least consistently entertaining.
Then there is the final "movie", a four-part OVA. That one is solid gold. Set between the two seasons, it finally explains how the drastic shift in tone and characters of Season Two came to place.
In my opinion, the production value mirrors the quality of the storytelling. I was not particularly impressed by the animation, dialogues, or even soundtrack (despite being written by Yoko Kanno) in the first half of Season One, but I felt like it became much better later on. Season Two and the OVAs are great in every regard. I watched the English dub, which is good throughout the entire series.
All in all, I'd recommend Darker Than Black if you don't mind sticking through the first twelve or so episodes. If you're looking for instant gratification, perhaps you should look somewhere else.
