Writers and readers both love to discuss, and maybe argue about, what constitutes "good" prose. From the readers' points of view, the definition really comes down to a matter of taste -- at least, that’s the conclusion I usually end up drawing from these discussions.
Some people enjoy complex sentences and unusual words. Some people hate them. Some people hate short sentences and basic vocabulary. Others like them. And so on.
It occurred to me that we might look at the problem from the other side: the writer's point of view. What constitutes good prose? Prose that has the effect upon the reader that the writer intended it to have.
Does the writer want the reader to zip through the story and enjoy it as an entertainment? That will require one style of prose. Does the writer want the reader to experience the story as an immersion into a strange and foreign place and time? That will require another. Is an incident supposed to be funny? Humor demands a certain choice of words. Is the incident supposed to make the reader get all teary-eyed? Then the writer had better avoid that distanced, ironic humor.