Moshfegh is a good writer. She's good at writing short, zippy sentences with active verbs and lots of concrete detail. Like this: "It was a drive like any drive to any cabin. It was up a dark and winding road. The last half mile or so was badly paved....I brought all my favorite things to eat and ate them almost immediately upon arrival: cornichons, smoked trout, rye crackers, sheep feta, cured olives, dried cherries, coconut-covered dates, Toblerone." Ooh, look at all those different foods. Could someone without an MFA list that many foods?
In all seriousness, this is a writing style that is very difficult to pull off. Moshfegh successfully removes all barriers to understanding; she has perfected a style that makes her writing as easy to understand as possible (I mean on the basic, can-I-figure-out-what's-happening-in-the-scene level). Like Hemingway without all the stuff you have to figure out through context clues. This means she is very easy to read---this book probably took me about three and a half hours. She sees her job as paving the road to semantic understanding so flat and smooth that nobody will ever break down.
But that's not what most people will remember about this book. The thing that will leave the deepest impression for 99% of people is her deep and abiding interest in anal sex. Now, how much should a contemporary book of literary fiction mention anal sex? Let's exempt books that deal with gay men (this book does not) since those will skew our measurements. Exempting those, how many would you say? I would say, for myself, that once three short stories in a collection manage to work in anal sex, I start to think of it as one of the fundamental themes, or at least a guiding motif, and certainly something that has to be mentioned in any serious analysis. You probably have your own number.