I got Shakespeare's Secret for Evalina last year, when the author came to visit her school. It is a signed copy, which I think is pretty cool.
The Story: Hero is in 6th grade, and she and her family have just moved to a new town. Her father is a Shakespeare scholar, which explains her name, and her sister Beatrice's as well. Where Beatrice makes friends easily and fits in well, Hero doesn't do so well. Her first day at school, a girl in her class brings up the fact that she has a dog named Hero, and the teasing begins. Things start to get marginally better for her when her mother sends her on an errand to bring something to their neighbor, the elderly Mrs. Roth. Mrs. Roth has a story to tell, about a diamond that went missing in Hero's new house, and she thinks it is hidden there. Mrs. Roth also has a young friend, named Danny Cordova, who is the most popular boy in Beatrice's school. He befriends Hero, and together they search for the diamond, which holds secrets of it's own.
The Good: The friendship between the two kids and Mrs. Roth is really heartwarming. Hero is a likeable character who I, personally, could relate to. The mystery was really engaging. There were bits of Shakespearean lore and history throughout the book, and I think it is never too early to start a kid on at least knowing who Shakespeare is. The characters were all very well developed and well written. I got Evalina to come to bed on more than one occasion by reminding her that the diamond wasn't found yet. The relationship between Hero and Beatrice is very realistic.
The Bad: I think Evalina was a little young for some of the themes in the book - lots of middle school drama, which I hope she never experiences (though she probably will), and since she had never really heard about Shakespeare before, I don't know that a book involving conspiracy theories about whether William Shakespeare actually wrote the plays was the best place to start. Knowing Evalina, she'll be spouting out that theory all over the place. There was also a part about Danny's mom taking off when he was a kid, and that made her really sad. In some parts, Hero lies to her parents and sister. Not the best role model all the time (but who is).
The Verdict: Overall, a super good book. It is recommended for grade 4-7, and though, as noted, some of the themes were a bit too old for her, she did well on the actual story and the reading. She was very engaged in the story (as was I). I think it would probably be a better one to wait a while for, simply so that there is more historical background for your child, but it is definitely recommended.