The review below was based on my first read of the Harry Potter books, ages ago and in Dutch. Updated reviews will follow after a reread (in English) I plan to do.
My gosh, this is quite the long story for a child to read. But I really liked it. Some called it too political, some a little bit boring, but for me this is one of three Potter books I like best (after HP and the Prisoner of Azkaban & HP and the Half blood prince). I liked the Order of the Phoenix and Dumbledores Army, but I couldn´t stand Umbridge (for understandable reasons).
Of course I believe everyone should at least have read this series once, so I would definitely recommend this book to everyone. But start at the beginning!