The first requirement for creating great new pop fiction is readability.
Quick pace is one way to make a novel readable. How far to travel away from quick pace is the difficulty-- how much meaning, how many ideas, how much background or description to add, in subtle ways, without destroying the pace.
Ever novel is a mix of elements. How one mixes the elements, in what proportions, determines how great the novel will be.
Note that The Great Gatsby contains fantastic pop elements, a sense of mystery, has a tight narrative and is readable. Fitzgerald expertly finessed some of the elements, like characterization, to be able to achieve this.