The scene takes place at the end of the novel, when Nick leaves Gatsby for the last time. In dealing with the petty and shallow people of the East Egg, Nick has seen how inherited wealth and superficial social standards are meaningless compared to Gatsby's true love and his passion, which comes from his heart.
"They're a rotten crowd," I shouted across the lawn. "You're worth the whole damn bunch put together."
I’ve always been glad I said that. It was the only compliment I ever gave him, because I disapproved of him from beginning to end.
(Fitzgerald, The Great Gatsby, mrbye.com)
Nick has changed from the beginning, when he was trying to insert himself into the social circles of the East Egg for fun and for personal gain. Initially, when he realized that Gatsby was lying about his past and misrepresenting himself, Nick feels suspicion and distrusts him. As the story progresses, Nick realizes that he and Gatsby have more in common than the other residents of the East Egg, and comes to like him better than the others; after his death, Nick realizes that he feels uncomfortable in the East Egg, and resolves to never return.