I consider "La cucina" neither particularly well written nor particularly well plotted. In addition, its aesthetics fails by a long way to justify the author's claim to have written "a novel of rapture".
A remark in advance: I'm a German reader who read the book in its original language.
Prior's writing style isn't something to be remembered for a long time. Mostly, she tells her story in a dry, report-like way. Although she has lots of outwardly dramatic events to recount, she rarely spends more than a few sentences on those, be it violent deaths, accidents, or whatever, and then goes on to continue the story. She needs incredibly many characters, so many that she never even starts painting a coherent picture of them. Even the main character, Rosa, isn't shaped in an understandable way. We get told that, after losing her first love, she goes away and doesn't have any relationship with a man for 25 years. All of a sudden, she falls for a chance acquaintance, who is immediately grasped by her now, suddenly, erotic radiance. I don't claim that this can't be explained -- I claim the author fails to explain the inner workings even of her main character.
The story hasn't become famous for its plot, but for its combination of describing both voluptuous dining and coupling. But a few remarks on the plot might still be in place. After having read the announcement on the back cover, the reader can very much predict what happens in the first three parts of the book. Although the author introduces lots of bizarre people and events, the main course of action doesn't present any surprises. There are one or two towards the end, but they, like the last of the four parts in general, don't make an essential contribution of the story.
My main point of criticism, however, is the book's aesthetics. The author wants to give a baroque picture of voluptous Sicilian life, its main sources of pleasure being delicious food, and boundless erotic pleasure. Alas, her limited stylistic capabilities prevent her from telling us anything outstanding about those, and sometimes have the opposite effect.
How much love to her subject, her main characters, and people in general, does an author have who lets Rosa tell us that "multiple births are as common about Alcantara women as they are among sows"? Should we go into raptures by meeting Rosa in the first pages heavily sweating across some pasta dough that she is kneading? Apart from scarcely appetizing scenes like this, Prior's descriptions of preparing delicious meals could have been taken from a cookbook, transforming each rule into an "I did..." sentence. So, for someone who likes descriptions of good food, there certainly are a few present, but they don't have more artistic value than the recipes themselves.
What can be told about the erotic sides is even less promising. Those who look forward to read the book mainly for its lovemaking scenes should be warned off, as only the third part, 55 of 267 pages long, deals with Rosa's relationship to her lover. It's truly a matter of personal taste whether you like detailed descriptions of food eaten from Rosa's bulky body, together with unambiguous hints on that bulkiness. The main flaw, however, is that the author again hopes that putting together the description of partly common, partly bizarre techniques might evoke rapturous sensations in the reader. When Rosa tells us '"God, you're beautiful," he said. And he meant it; and I was;..." it gets clear what stands in her way: again this matter-of-fact reporting style that won't add anything to the zillions of love scenes that have been written in the past centuries.
So what's the benefit of this book? Given that most readers of fiction are women, its success might be explained by the promise it makes. It's a fairytale, and its message to its female readers is: no matter how nondescript, bulky, and frustrated you might be, tomorrow you may run into your perfect lover, who will share not only your bed, but even your main interests, and will adore you as a goddess. So, if you already have Cinderella in your bookshelf, you may skip La Cucina.