The bigger difference was that all those mini arcs that seemed so episodic and pointless came back together at the end of the series in some appreciable (though occasionally minor) way. The second or third arc was with the girl who was wavering between becoming a contractor or rotting away, only to become a full blown contractor and get taken in by the Syndicate. She reappeared at the end, very much like Tanya did here, and was part of the forces fighting against Amber's. She even killed a few contractors so that Amber had to waste energy to bring them back. That told us in full how the Syndicate treats their contractors, like little more than weapons, and that the Contractors themselves are either brainwashed or don't really mind. Tanya actually had to directly mention that to give a similar description of the Russian forces.Originally Posted by RyougaZell
Each of the other arcs developed characters or relationships so that we might actually feel something when they died in the final arcs. How much screentime did Hazuki really get? If we weren't told that she found Youko to be special, would we really even know? Just the one kiss, "to get the taste out," was ambiguous enough that we wouldn't even suspect it. I for one was not saddened or thrilled by her death, it was more of an, "Oh, she's dead now, I wonder (but doubt) if Hei really killed her," moment.
So despite the different format, I do think we should have expected more out of the single arc that should not have left any loose ends. Mini arcs seemed to work quite well.