Man, looks like everyone hated the "Hollywood Michael Bay Happy Ending" lol, I'm not gonna complain, to me that Vampire arc was ridiculous. So what, they saved the world and everyone is happy. Kei is a freaking world hero. At least its not one of those complicated "open ended" or cop-out endings that everybody hates. Yeah I agree it felt rushed and had many holes but at least WE GOT AN ENDING.
Who knows, now that it's officially over, maybe another anime adaptation can be made and they could right the wrongs that many fans say this series had. But c'mon guys, yeah Gantz is all about the gore, misery, and people dying that normally wouldn't but oh well, it could have been worse. Kei lived, he's got his girl, it's over. But yeah, it was one big clusterfuck of a final arc lol