In an Instant is a two part memoir, one about how the Woodruffs met and the other about Bob's recovery from the injuries he received when an IED exploded under the vehicle he was riding in. For the most part, Lee's memoir covers Bob's recovery. Bob's memoir in turn covers their courtship and marriage.
As Lee explains in the "About this Book" section, the process of writing was therapy for her during those tough weeks while Bob was in the medically induced coma. Bob's contribution to the book was also therapy and served as a way for him to recover. He had to relearn how to speak, write, walk and all the other things most adults take for granted.
For the gruesome details of Bob Woodruff's injuries, In an Instant is a fairly easy book to read. Lee's passages are by far the more interesting half of the book. Her descriptions of what happens to the body when it is hit by an IED are frank, raw and unglamorous. Bob's memories of his marriage and early career may be of interest to his fans but for me it interrupted the flow of an otherwise interesting book.