In short, how is Nick's story resolved at the end of the novel, and what does his interpretation of Gatsby reveal about his own character? Does Nick,

I agree, Nick is alright. It is hard to lose track of Nick’s story throughout the “Great Gatsby.” If characters such as Gatsby are the life of the party—then people like Nick are the individuals that float around the edge of those parties observing but never observed. He is much more introverted, and in a sense, more complicated character. He provides more depth to the story than Gatsby’s character could ever allow.
By the end of the story Nick was the only player that understood any depth of Gatsby’s character. Tom was quick to label Gatsby as a fraud or thief, the many patrons of his party labeled him murderer or romantic, even Daisy failed to see past the social construct that so easily trumped her love. Nobody, except Nick, was perceptive, or even cared, enough to see him as anything but a caricature. Even his father appeared clueless when arriving to his funeral. Fitzgerald displays a world that his totally out of touch with empathy or the wherewithal to show any genuine compassion or interests. As a result Gatsby died, and was never seen as anything other than a criminal or socialite.
The fact that Nick makes the statement that Gatsby “turned out all right at the end” proves the point that the line between good and bad can sometimes become blurred. Is somebody with dreams and aspirations necessarily bad because illegal activity is the only way they see to facilitate them? Gatsby put in the work tirelessly: doesn’t he deserve to be rewarded? He saw something that was otherwise unattainable to him and reached for it no matter the cost. And Gatsby, to a certain extent, was successful. If the American dream is a lie and we are sold short from its promise at birth: can you blame him for not playing by the rules in a game that has none? Compare Tom’s work ethic to Gatsby’s, now imagine the playing field being balanced: who do you imagine coming out on top and living the ideal life portrayed to us through fake propaganda? In a more sensible world: Gatsby would have won the girl, kept his life, and made his fortune the right way—but this is not a sensible world. This is why Gatsby turned out all right—because he had oranges and truly made lemonade, if not for an instance; he at least deserves credit for that. Despite his short comings one can affirm that he was a person of high character, and save for nick, there are not a lot of characters that you can say that about in the novel. Nick was alright from the beginning, but just needed to re-discover that—which is why he provided the novel with such an unbiased view point. There was a sliver of humanity still left in him at the end of the novel, which is why he had to move, before he became as inhuman as the other characters that populate the novel.