So this was, for all intents and purposes, the end. I was worried that I'd be disappointed in it. I think I'm generally pleased, though that's not to say I don't have my complaints about it.
I suppose my biggest complaint is that it really went for the "good ending" thing that required some contrivances along the way. The reveal that Hei fused with his sister at Heaven's Gate...is actually not really one of them. It explains why he toes the line between human and contractor that nobody else seems to. It explains how he's held responsible for the Heaven's Gate incident. I guess my only issue are the contrived physics of it all, though I suppose this series has always been light on accurate physics.
I enjoyed the scene where Hei basically encountered everybody he's met along the way. The albeit brief conversation with his sister was a good cathartic moment. Though like I said, it results in a sort of "have your cake and eat it too" ending where everybody gets to live (well, not everybody. The old guy is still dead. Mao's still dead. And Amber used the last of her energy to turn back time enough for Hei to execute the proper plan).
As for Pandora and the Syndicate, Kirihara exposed them, and now the director is in jail. I think this sequence resulted in Kirihara becoming my favorite character in the series. Though I'm not sure how she managed to sneak in a recording device when they basically combed her for everything. I may have overlooked something.
So the "good" ending isn't necessarily good. The contractors and humans are still fighting and there's still chaos. But Hei, Yin, Kirihara, etc. all get to live on. What lies in store for Hei is unclear, but he'll be fine.