I'm a Janeite, so this was my kind of book.  I think it would be too slow and repetitive for anyone not in love with Jane Austen, her people and her time and place.  I liked being in on her somewhat snide evaluations of people she meets and situations she encounters, and the letters do soften the 'authoress,' Jane Austen, for me and let me see more of the daughter and sister, Jane Austen.  I loved the little details of daily life, writing to her sister and asking for two pair of stockings or some gloves from a particular shop or supplier, the contemplation of new dresses, the yardage to be purchased and then given to the dressmaker, the women of the family sitting in the parlor at their 'work,' making a dozen shirts (by hand with tiny stitches) for a brother soon to go to sea, the breakfasts, teas, dinners - with the food and drink seldom described.  You'd think they didn't eat!  But then, this is England, not France.  Anyway, the book is a time travel vehicle.  People die.  Babies are born.  Mothers die.  Fathers remarry.  There are constant flirtations and courtings.  There is the endless finagling for the right mate, someone of equal status with money, and not too awful.  Jane and her sister don't seem to take the deaths very hard.  I suppose with someone always dying, and untimely death being so much harder to avoid,it was a matter of course.