If you enjoy learning about the British monarchy, especially the Tudors, you will love this novel. Although fiction, the novel gives excellent insight into the rule of Henry VIII, Edward VI, Mary I, and, of course, Elizabeth I. It also is rich on detail about life at the time, from the use of cosmetics to palace life to fashion to food.
The novel also gives a voice to one of England's greatest and most fascinating monarchs. It is impossible to know how accurate Miles' portrayal is in terms of Elizabeth's emotions, motivations, etc., but she strictly follows historical events, even including small factual events, such as Elizabeth's inscription on Dudley's (Earl of Leicester) last letter and several important quotes ("This is the Lord's doing and it is marvelous in our eyes..."). The novel also includes handy family trees at the beginning and a list of "persons of my history" at the end for reference.
I agree with other reviewers who noted that much time was spent on Elizabeth's favorites, including Thomas Seymour, Robert Dudley, and the Earl of Essex, but it is true that these men were the queen's favorites, even if they may or may not have been lovers. The queen is portrayed as a silly, flirty thing at times, but mostly it appears as if she never loses sight of who she is. She is also portrayed, in turns, as vain, brilliant, jealous, clever, manipulative, etc., all attributes of a person, even a queen.
A few criticisms of mine include that the portrayal of Elizabeth's relationship with Seymour was only partly factual. That he invaded her bedroom regularly to tickle her and kiss her was true, but I have read that she was not besotted with him, but rather annoyed at his attentions, so much that she asked to be sent away. Also, I did get tired of the long tug of war with the Earl of Essex, since Elizabeth the narrator mentions multiple times that she had no feeling for him, he was dead to her, she felt nothing, she felt only coldness for him, she realized he was a traitor, etc. after each of his progressively more dangerous escapades, but it takes a truly drastic act to make her fully return to her role as queen with him rather than woman (which, as with everything, follows historical events, but the details of her emotions seem especially exaggerated for dramatic value at this point). The end of the relationship in the novel does bring a twist of her reasons for acting as she did, which imply that she knew what she was doing all along and somewhat redeem the repetition of her feeling nothing, then being in love, then feeling nothing again.
Overall, the reader cannot expect this novel to be the embodiment of the real Elizabeth's voice, thoughts, and feelings, but it is as good of a surmise as any, and it is pleasurable to imagine her voice in the novel as real. The novel's other great value comes in the form of the historical facts I detailed earlier, giving the reader a fascinating look at the Tudors and life at the time.