I have to disagree with those who consider J. K. Rowling's work subpar. Putting down real money to buy a book is a real measure of how many people find a work important; add together how many people want to spend hundreds of hours reading those books and you have a better metric of a work's place in literature than counting how many people click their mouse in some online survey. Hundreds of millions around the world parted with their money and their time in a kind of vote for the HP books. Millions more stood in line at midnight to buy the books as soon as they could get them and went home and read them.
Physical science gives us hard facts about a reality that never changes but literature has to reinterpret the human reality--the times they are living in--for every generation. Regardless any post-modern, deconstructionist foo-foo about what makes great literature, the HP books pass the test for the children of the generation in which they were created. I believe that fact qualifies them to have entered the "great dialog" that is literature without regard to their appeal to earlier or later generations.
I agree it is a tragedy that these books are not available as eBooks because eBooks in some form or other are quickly becoming the means of presenting literature. As we all know the HP books are not the only important literature being left out. I think To Kill A Mockingbird to name just one, is part of that great dialog and another important work that has yet to join the steam of modern publishing but that's a different thread.
Can Rowling continue to interpret this present age in a way that rings true for an older group? It's such a rare thing for any artist to accomplish even once that I doubt it can happen but I want to read this new book regardless.