I think the success of a story boils down to whether it provoked a reaction in the reader (and that it was the reaction the author wanted!). The best way of doing this is to create interesting characters, drop them right in it metaphorically speaking, and see how they react. Your characters have got to care about the outcome of whatever situation you've dropped them in. Your readers have got to care about what happens to your characters.
So what reactions are your characters provoking? The worst reaction is indifference because it will mean a reader is either put off by your characters not evoking a reaction. Alternatively the reader will also be indifferent to your character and story.