Happy Lost Day! Sorry, but I'm in the group of the finale being good and I don't mind the "unresolved" issues (like no explanation for the islands powers).
Because much like The Walking Dead, it's not about the island, or zombies, or anything else like that. These shows are character driven, and designed to explore different facets of human emotions and the human psyche.
Sure, Lost took place on a strange uncharted island that had healing powers, could only be found if you travel to a certain spot in a certain direction at a certain time, and could travel through space and time... but that was just a device to highlight what the show was really about: science versus faith. Jack's search for answers, what is the island, where are they, how do they get home, represents the science side of human understanding. Everything MUST be examined and explained. Locke's man of faith just accepted the island; he didn't care why he could he walk, he was just happy he could. In the finale Jack took on the role of protector of the island and switched to a more faith based approach, it's unfortunate that many in the audience didn't follow suit and are still seeking an explanation.
And The Walking Dead exists in a world that has been overrun by zombies, but that's not what the show is about. That's not even what the title of the show references! The walking dead are the survivors, because they've already lost. They're fighting and trying to survive to the next day. Fighting the zombies, fighting themselves, and fighting other survivors who react differently. They have all had to make compromises, have killed the innocent, and lost loved ones too soon. But for what? Eventually they will all die, by sickness, old age, or unnatural means, and then they'll be zombies too. What's interesting is what drives each person to keep going, what they hold to, and how they react to the situation around them.
That why I feel sorry for those who watch these shows with the expectation of having not necessarily a happy ending, but an ending that's wraps up all the loose ends and explains everything for them. They're missing the point. They're only interested in solving the mysteries and seeing graphic zombie fights, and they're missing out on what the show is really about. Humanity.