Yay, a Harry Potter thread! Some more detailed thoughts then...
Anyhoo. OK, so now I've read the third book, and I'm a quarter of a way through the fourth.
First, the bad. Namely that I think the fact that the books are so wildly popular is more a testament to the state of reading among youth nowadays than it is to the books themselves. They're not the best books I've read, and there's not really anything in the books that is revolutionary compared a number of other novels... just that kids don't usually get exposed to those other novels in better circumstances than cruddy reading classes. (I mean, heck, I've been a voracious reader since I first learned to read, and I still loathed reading classes... I can only imagine how a kid less inclined to reading must feel.)
Now the good: Don't read too much dour into my previous statements... I still think they're very good and very fun books (or I wouldn't still be reading them, heh) Plus there's "nothing new under the sun" anyway, and Rowling gives a very creative and fresh spin on everything.
Even better, this is one of the few popular kids' trends within my memory I would consider not to be brain-dead on some level. (That's not to say I think all other popular kids trends are *bad*... there's very few I'd give that label to. Just that most of them aren't exactly intellectually or culturally stimulating.) Besides, it might inspire kids to read more sci-fi and fantasy.

Oh, and I still love the Weasleys. I would have loved to have a family like that to hang out with.

I think I'd particularly enjoy getting along with Fred and George...
Peace & Luv, Liz