Beats me. All I can tell you is that I fell in love with it when I read it for the first time as a teenager. If not "lyrical," then in some way the smoothness (for lack of a better word) of the writing really drew me in.
If not "maverick," then it was at least very "modern" at the time; a novel of its day and age. Perhaps the fact that a book written at the height of the Roaring Twenties can make me feel, a century later, that I understand something of the period indicates that Fitzgerald was a perceptive observer of his society.
I've read it three times for different English classes. It's one of the handful of assigned books I liked immediately on reading and enjoyed again on rereading. And Fitzgerald was seen as one of the premier American stylists of his time, which doesn't necessarily mean lyrical. There was an attempt starting somewhat before WWI to bring the language of literature more in line with spoken English. Fitzgerald, Hemingway, Steinbeck, Faulkner, Gertrude Stein, Sherwood Anderson, Ring Lardner, all of them and many more, were working in that direction, taking their cues from Mark Twain and consciously pushing against the tradition of more formal language and sentence structure of Henry James and much of his generation.
As Victoria said,
Gatsby gives a sense of its era and the aspirations of those living through it. And if you look at it in light of what came just after, it's like a kiss off to the Roaring Twenties. Fitzgerald was fascinated (if not obsessed) with wealth and our class system. Fitzgerald saw sadness, disappointment and even ruination in the nouveux riche thinking that wealth alone could attain the upper classes.
For some reason that always reminds of this rhyme,
And this is good old Boston,
The home of the bean and the cod,
Where the Lowells speak only to Cabots,
And the Cabots speak only to God.
