I don't actually own this box set, but I'm too lazy to add each individual Potter book.
I think the books are getting better and better. Book 1 I would only rate as 3.5 out of 10, but book six is a cracking 10.
The books are getting increasingly dark and exciting. They're easy to read, but I wouldn't want young children reading book six. It'll give them nightmares.
I can't wait to see what happens in the next book.