I had avoided writing about the Harry Potter series. These books are generally well known, and others have done very in-depth commentary on them. So, what I will do is look at the series, overall, for those who haven't actually read them who are on the fence about them.
I started reading the books long before I went back to school to earn my M.Ed. Lyric Mezzo, who had introduced me to other fantasy series, loaned me a copy of Harry Potter and the Sorcerer's Stone back in the late '90s. Only after having borrowed all the released books from her did I decide I would get copies of my own - after another friend gave me a copy of a new release in hardcover. I've even recently gotten the older of my little sisters - who is 27 - to read them. Just the other day, she gave me back Chamber of Secrets and told me it would be okay if I brought her the next one of my "nerd books"...
The series consists of seven books, beginning with Harry Potter and the Sorcerer's Stone. This is where we meet Harry Potter, an eleven year old orphan, living in the cupboard under the stairs in the home of his aunt and uncle. Harry learns that his parents were wizards, and that he is one, too, and that he has been accepted to Hogwarts School of Witchcraft and Wizardry. That is where lots of people have a problem with the series, thinking it promotes witchcraft to children. People who think that, in my opinion, haven't read the books and don't know what the heck they are talking about. For those of you who lean this way, I invite you to check out Fantasy Fiction for Christians, where you can find discussions of the Christian imagery that can be found in the books (WARNING: there be spoilers there!). There are also books on the subject, as well as at least one "anti-Harry Potter" commentary book (none of which I have read). Let me just say that in the Harry Potter books, whether one is a witch or wizard is something you are born with and is not something that can be acquired. Anyhow, Harry learns that his parents were murdered by a "dark wizard" called Lord Voldemort, and that Harry is the only one to have survived when Voldemort decided to kill them; most people think Voldemort died when Harry became "the boy who lived", but there are some, including Hogwarts' headmaster, Professor Dumbledore, who believe otherwise and are on guard against Voldemort's return.
Harry Potter and the Sorcerer's Stone covers Harry's first year at Hogwart's. As mentioned above, Harry turns eleven at the beginning of this book. I think it would be appropriate for a child to start reading the series about this age - 10 or 11, though I had a student in my 3rd grade student teaching class (who was 8 or 9 at the time) who was reading it. Each of the subsequent books are the succeeding years of Harry's life.
One thing I will say is that the books get progressively darker in plot as they go along. So, even if a child is a good enough reader to get through all seven books right off the bat, I'm not sure that most kids would be mature enough to deal with the darkening plot line. I would really recommend that parents read the books themselves in order to be able to make the judgment about whether or not their child is ready to read them. The first death - a murder - of a character occurs in Harry Potter and the Goblet of Fire which is the fourth book.
Harry Potter's world is one of fantasy: magic spells, fantastical creatures, and all the conveniences enchanted objects can provide. But, it also presents situations where characters must make choices between right and wrong, and as Dumbledore says: “The time is coming when we must all choose between doing what is right, and doing what is easy.” The lesson being: sometimes doing the right thing is the difficult choice. This theme carries throughout the series, in this fantasy context. I think that parents could use the books to talk to their children about making choices, being honest, helping others: Does Harry always make the best decisions? What other choices could have been made? Is it right or wrong to keep secrets? Does evil really exist? The possibilities, I think, are fairly endless.
So, the series, in order:
Harry Potter and the Sorcerer's Stone
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Harry Potter and the Goblet of Fire
Harry Potter and the Order of the Phoenix
Harry Potter and the Half-Blood Prince
Harry Potter and the Deathly Hallows
There are other "Harry Potter" books by Rowling, but they aren't really about Harry. They appear to be - I have not read them - "books" mentioned in the actual Harry Potter books: Tales of Beedle the Bard (to be released December 2008) and Classic Books from the Library of Hogwarts School of Witchcraft and Wizardry: Quidditch through the Ages and Fantastic Beasts and Where to Find Them (2001).
So, while I have very much enjoyed reading the Harry Potter books, I know not all parents are okay with them, and that not all children will be ready at the same age to deal with the progressing plot line through all seven books. But, before you decide to not allow your kids to read them, I would ask that you read them yourself first and make an informed decision.
On a related note, unless you've been living under a rock, you are likely aware that the books have been turned into a highly successful movie franchise. Like the books, the movies are getting progressively darker. While these movies are based on children's books, these movies - especially as the series has progressed - are NOT for small children. I've seen (and own) the already-released first five movies. A small child - and possibly not-so-small kids - might get very scared by these movies. The sixth movie is to be released July 17, 2009. As with the books, screen them first for young children.