Nicholas Lezard takes issue here with JK Rowling's prose, in an article which I agree with entirely (despite having read all of the six books so far). I've been wondering whether the Potter books will last as children's books and I think they will - but in the same way that Enid Blyton's books have, rather than as the kind of children's classic that can be appreciated by all readers. Kids still read and love Enid Blyton, but there seems to be a definite cut-off point where one suddenly realises how empty her writing is; as an adult, I find them entirely unreadable.
The problem is not just with Rowling's prose, leaden though that undeniably is. There's a greater failing of imagination which means that although Rowling's stories work in theory, they're strangely lifeless in practice. The first three books, in which the story is limited to being a boarding school adventure with magic, work better than the later ones, in which Rowling's attempts to move the overarching story to the grand epic scale fall terribly flat. The focus of the stories moves to become a struggle between good and evil, but Rowling's skill at narrative isn't strong enough to make this gripping. We're also not given enough information about what the results of Voldemort's victory actually would be: compare this with Susan Cooper's excellent The dark is rising sequence, in which the implications of the Dark rising are explained, and we are told that the last great rising of the Dark was during the barbarian victories over roman civilisation.
I've enjoyed the Harry Potter books that I've read, in the superficial way that I enjoy trash, but I think that what children love about them is the plethora of delightful details, and the reassurance of seeing the same situations repeated again and again: the triumph of the children over the grown-ups, the way that breaking rules and disobeying authority figures comes right in the end as the disobedient kids save the day, even the orphan figure finding love and acceptance in a new world. Clichéd situations and glorious details - these are the standard techniques of trash fiction: think of Ian Fleming's absurd levels of detail about Bond's shaving products, or any of the 1980s shopping and fucking novels. But in JK Rowling's case it feels much too borrowed and stale to ever really come alive: she's not borrowing from the myth and religion of the past as Susan Cooper and CS Lewis did, she's borrowing from people who've borrowed from that.
I will probably read the seventh book, eventually, as I have a nerdy obsession with completeness. But whether my children will read or know these books is certainly doubtful.