First of all, let me say that I started to read the Harry Potter series in order to improve my English (although I've exceeded the proper age easily at that time already). My idea was, that children's books were easier to understand than those for adults. So far so good.
What I didn't expect was, that the books would be quite unique so that I've re-read them ever since I've laid hands on the first one.
It has been described before from persons who are certainly more able than I am, that Ms Rowling has created something special - a world which is not that far away from the ordinary one but still different, full of magic. However, the inhabitants of the other world have to struggle with common problems, too: distrust against each other, enviousness, lovesickness, .... Those are problems where no magic can help.
To be honest, I like reading children stories or books for young adults. Somehow it seems to be more suitable when an author invents fantasy worlds for children than for adults - they already live in an own world full of wonders.
I liked the idea of describing a young wizard being educated, the daily life in a boarding school, his growing-up with all implications of adolescence and of course the encounters with his adversary. As a conclusion I can only say, that I loved all the books - and still do. So my recommendation can only be: read the series and enjoy the story how it develops through all the books.