I, too, don't understand the contempt felt for HP. She owes a great debt to Nesbitt, Carroll, Tolkien, Lewis and who knows who else, but they are good reads. They may be "beach reads", but they are not tripe. I disagree with those who say they are literature, but to stimulate discussion about larger themes or about marketing phenomena or about the popularity of fantasy fic today etc, HP works just fine.
I don't see the point of criticizing them for the very attribute that makes them popular: they are plot driven novels rich in details with characters we come to care about. The oddest bit is how adults have taken to them. If HP hadn't taken over the NYT's Best Seller List for some months, spawning a children's BS List, I wonder if we would have all this talk of how bad the books are. I've been rereading children's and YA (young adult) books my entire life. A well written book is a well written book. With that, I will say that an enjoyable book is an enjoyable one--they are neither mutually exclusive but also not to be found within each novel, either. IMO, one puts up with Rowling's weaknesses because one wants to enter that particular world. She didn't set out to write Great Literature; she set out to tell a story. IMO, the worst thing that happened to her was the massive success because it made her editors reluctant to get out the scalpel and never even touch the axe. This shows in the later books, and not to her credit. The epilogue in book 7 is a crime against all storytellers for just one example. It is so poorly written that words fail me.
Of course there are better writers out there. I don't quite see how Rowling's success takes away any of the talent of these people or the appreciation for their work. (Hell, there are excellent writers out there who aren't even published). There are much worse writers, too--some of them published and popular (Stephanie Meyers comes to mind). It is simple snobbery to disdain that which is popular. Sometimes the contempt is deserved (as in the Twilight series), and sometimes it isn't (HP).
I don't see why HP has to be considered Great Literature in the first place. Is only GL deserving of great accolade? As someone said upthread, HP deserves a place in discussions about fiction if only because of the success of the books. Writing is a fascinating art form, but only a very few books can be considered true art, IMO. The world is content with a good story, something I'm glad of, aren't you?