This book wants to be Jane Austen with magic. It's entertaining enough if you like Regency domestic dramas and are looking for a light read, but that's the best I can say for it.
Shades of Milk and Honey follows the typical Austenian marriage plot: two daughters of the landed gentry seek eligible husbands, people are mannerly and attend balls and dinner parties, etc. The book seems to be set in an alternate world, where magic is considered a ladylike accomplishment like painting or piano playing, although the existence of "glamour" does not seem to have altered the history or culture at all.
I was initially drawn in by the premise and the quasi-period tone, and this proved to be a quick read: just under 300 pages, and very easy reading despite the suggestion of 19th-century style. The plot is entertaining, though entirely predictable, and proved compelling enough for me to finish quickly. But in retrospect it was unsatisfying, borrowing far too heavily from Austen rather than breaking any new ground. Almost the entire cast consists of stripped-down copies of Austen characters: Jane, our protagonist, is a mixture of Elinor Dashwood and Fanny Price; her younger sister Melody is Marianne Dashwood with a liberal dose of Lydia Bennet; their parents are Mr. and Mrs. Bennet; there's a Mr. Wickham, a Lady Catherine de Bourgh, even a neighbor who reminded me of Harriet Smith.
And they spin through the expected scenes (walks in the garden, strawberry-picking, etc.) without spark or individuality; characters' relationships with each other are uniformly one-note and their interactions bland and repetitive. Jane is the only one with any depth, and she's too dense to be believed. This is a woman who can't even guess who her sister's secret lover is despite the fact that he visits the sister every day and both are acting besotted. In the end the book feels like fanfiction: you might read it because you like Austen, but there's no reason to be interested in Kowal's characters for their own sake. And the plot unravels at the end, with an action-heavy climax that feels out-of-place and melodramatic in a book that's otherwise stuck slavishly to Austenian tropes, followed by a hasty wrap-up. As for the romance, to the extent it works at all it's because the novel's structure makes it inevitable, not because there's any reason for the two to be attracted to each other or believable growth of affection between them.
As for the writing, it's readable, but very unsubtle and often abrupt. Kowal has a clunky tendency to repeat words several times within a couple of sentences, and to tell the readers what she's already shown. There are also some anachronisms in the language: for instance, Jane identifies another character as suffering from "depression," a term not used to refer to the psychological condition until the 1860s, and more importantly, one that rings jarringly modern for the Regency illusion the book tries to sustain.
The final verdict: Okay if you're into Austen fanfiction and looking for a beach read, but not a book I'd recommend.