I admit that I put off reading these books for a long time because they seemed such a blatant rip-off of Harry Potter. But I happened across the first book of the series in a Goodwill store and decided to give it a go. While they are similar to the HP books, the first book in the series is still enjoyable. I would recommend them to a younger reader- maybe 8-12 years old. Here is the summary from Barnes and Noble:
Septimus Heap, the seventh son of the seventh son, disappears the night he is born, pronounced dead by the midwife. That same night, the baby's father, Silas Heap, comes across an abandoned child in the snow -- a newborn girl with violet eyes. The Heaps take her into their home, name her Jenna, and raise her as their own. But who is this mysterious baby girl, and what really happened to their beloved son Septimus?