There was so much just in the book description that appealed to me--time travel and Jane Austen?! Sign me up! Other reviewers have mentioned the attention to historical accuracy, and as someone who has studied and read extensively on that time period in England, the setting felt very accurate. Sometimes books are accurate but feel like research info dumps; because Rachel was an outsider looking in, the little details like the crazy medical theories and the stench and the funky toothpaste flowed seamlessly with the story. I was apprehensive about the portrayal of the Austens themselves. I've read a couple other historical fiction pieces that have Jane and/or Henry Austen as periphery characters, and never have they seemed quite so real as they do here. I actually loved the characterization of all the Austen brothers. Henry is so believably charming but irresponsible; I loved Rachel's comment that all the Austen characters named Henry have a bit of that persona. Edward is the right amount of affectionate but reserved, Frank is jolly (and just the sort of affectionate sailor that we expect to love from reading Persuasion), and Cassandra is cautious and a bit of an enigma. And Jane herself is real and believable to me. The wit of her novels and letters is there, her intelligence is obvious, she's a woman of her time who reacts convincingly to Rachel and Liam, and she is lovable. When she starts to decline from the mystery disease of which she actually died, I'm as upset as Rachel is. 
 Time travel can be done well or poorly (Connie Willis being my favorite at madcap or profound; Jodi Taylor is also great at making it madcap fun), and this time travel seems relatively well thought out. In some time travel stories, there's this idea that history will self correct any little changes that you make. Here, Flynn lets the changes play out, and the last part of the book is poignant and thought-provoking as the characters work through the consequences of their actions in regency England. As I described the plot to my family at the dinner table tonight, even my ten year old was fascinated by the sorts of dilemmas that Rachel and Liam face at the end of the story. When you're talking about imaginary historical characters, you might make one decision. When you're talking about one of the greatest writers of the English language, does it change things? Plenty to think and talk about here. And how would we think about Jane Austen differently if we knew more about her life, if she'd lived to write more novels, if Cassandra hadn't burned those letters that might have contained sentiments that would inevitably have offended someone enough to initiate a protest, a twitter campaign, a demand that she be removed from our syllabi? Like other masters of their craft who died young (Keats, Mozart, etc, etc), we're left to wonder if she would have continued the same level of brilliance for decades. Late in the book, there's a reference to Trollope that I found apt. Is he a second-tier writer because he managed to write so many novels, some of which are just not as fun as his best? This book makes me want to sit down with some of my college English professors and have a fun session of what-ifs. 
 And I like Rachel a lot. Liam is more of an enigma, though I like him more as Rachel likes him more, but I like that she likes a lot about the 1800s while simultaneously missing modern conveniences. The fact that she's spent a lot of time living in extreme locations doing disaster relief work means that she reacts just the right amount to the relatively primitive tech of the Regency. I like watching her fall in love with the Austens as people, not just as subjects. I like that her medical knowledge helps some, but she's not an obnoxious know-it-all who can diagnose any medical disorder under the sun *cough*ClaireFraser*cough*. I like that she is nervous, that she makes some mistakes, but that she is trained well enough to get by and make a convincing Jamaican tobacco heiress. Too often, such heroines are either so well-trained that they're robots are so poorly trained that you wonder what kind of idiot would send them back in time. Rachel's a good mix. I buy her as 18th century Mary, and I buy her as future Rachel. 
 BUT. The reason this isn't a 5 star book for me is that the insertion of (PG-13 rated) sex, a somewhat tepid romance between Rachel and Liam, and several F-words just pulled me out of the world altogether. I get that any contemporary fiction nowadays is going to have people jumping in the sack together. I get that even among self-proclaimed Austen fans, the Regency bodice rippers and Outlander-type softcore porn are the norm. I get that we purist Austenites are often accused of being prudes because we don't necessarily think that sex is the be-all and end-all of a romantic story. I get that the author felt that by making her heroine someone who casually speaks of no-stings sex, she could somehow mitigate that sheltered nerd vibe. But it just pulled me out of the world. A forbidden longing, a romance developing between partners under the stress of having to pretend to everyone else in the world all the time? That fits with the story. See aforementioned time travel historical fiction writers who do this well without making things crass. A heroine who mentions repeatedly that it's been too long since she had sex? Who propositions someone engaged to someone else with crude and vulgar language? Nope. It's not that people weren't vulgar and sleeping around in Regency England. They were. But those details seem incongruous with all the other things we're reading about, because this novel is more than just another bodice ripper. While there are hints of Rachel and Liam's relationship being something real (and a beautiful final scene), it feels like they're just in lust with each other for most of the book. Austen herself alludes to scandalous behavior (Crawford and Maria, Willoughby and Eliza, Wickham and Lydia, etc) but doesn't take us into the room and show it to us in all its depraved detail. I'm unconvinced that this was merely because she was a product of her time; I'd like to think that she would still write insightful books about human nature that could be read by a 14 year old or 84 year old if she were writing today. Despite the many things I liked about this book, I won't be giving it to my mom or my daughter, and that is a bummer.