Fine for kids to read HP .. and it can help them actually like reading but, as with Enid Blyton, the standard of writing is not great.
I can't quite recall which books we dissected in P5, but I'm al;most certain we read one of the 'Lone Pine' adventures in P6.
These were slightly more complex and involved than Blyton, but equally interesting to the childs's mind.
I doubt any childs ave a genious would know the difference between author's styles; however if their imagination is stimulated and they find a need to delve into literature, then, seriouisly, does it matter whether or not the author was a literary genious?
For the record, I think Rowling was, and is, a very fine fantasy writer.