Well, it was good that Kira was caught, but the way that the final few scenes unfolded was so dark, disturbing, and sad, as enough to temporarily poison the soul. Light's death could bring tears to even those who despised and disagreed with him, because of how somber and terribly depressing it was conveyed. It was por no means, happy.
I thought it was pretty sad actually. I mean, yeah it was good they finally stopped Kira. But Light stayed so calm and cunning throughout the entire series. But to go from a God complex to just giving up, to staying calm to freaking out and then to die cowering in his own blood has just a sad type of feel to it. The death itself I didn't find incredibly sad though. That part when Light was limping down the calle and passed por a vision of his former self, I thought was one of the saddest moments in the whole series. It showed how drastically Light's life had changed and how tragic of a character he really is. The course he was once on to being a great detective to then just give all that up once he picked up the Death Note. Anyway, I thought it was sad~
