I wondered if it would be as the story began, however. The first part of the movie comes off a little cartoonish and over the top. Yes, I know Gatsby's parties in and of themselves were over the top, but this portrayal of it bordered on caricature several times. There may have been a little too much pushing the wildness of the scene without letting the scene tell its own story. Yes, caricature is the best word to describe how it was done.
Eventually, however, the movie settles nicely into the story, and the caricature is left behind.
From a literary point of view, I think much of Fitzgerald's poetic descriptiveness and sarcastic humor are missing. The movie doesn't have the same beauty as the straight words of Fitzgerald, but, once again, it slowly emerges over the course of the film. By the end, it is there... beautifully.
Now, for the seemingly controversial use of modern music in a period piece. As soundtrack and music that frames scenes, the modern music worked well. It was not distracting and served well for setting the mood. When music was part of the actual scene, however (a band playing a party, for example), the modern music was distracting. To see trumpets, trombones, and a drum set at a 20s party while hearing hip-hop is a big disconnect. But, this is confined to the early parts where I felt everything was a bit cartoonish anyway.
Some points of the original novel are left out, but in terms of making a movie, they were not missed. Overall, it stuck to the book well.
If you are like me, you'll sit through the first part of the movie thinking, "Uh oh, they really goofed this one up." But after a while, you'll see the beauty and true story emerge and be pretty happy with it by the end.