You know, i think I would actually rather have my kids read The Golden Compass than Harry Potter.
Harry Potter is not, to my mind, evil or going to drive kids to the dark side. But it is essentially fluff. Rather poorly written fluff. It isnt really Christian or non-Christian, it is pretty much in line with popular culture on the subjects it treats, where popular culture is fairly reasonable.
The Golden Compass is actually a well written book, with much more serious and subtle themes. It does engage directly with a Christian worldview, and it isnt a Christian book, but it takes the questions it treats very seriously, as if they are important and deserve intelligent consideration. And there is a kind of consistency in the imaginary world that it presents that brings out some very interesting ideas about God, about the Fall, and about the nature of good and evil.
One of the main themes it explores is the idea that in the Fall, we became as Gods, knowing good and evil, treating it through a coming of age story that spans the three novels. It is hard to imagine HP even attempting to treat something that sophisticated, and I think if it tried it would fail because the imaginary world has no internal metaphysical consistency.
As far as general attacks on fantasy - I think one problem people who whig out about that stuff have is that they think that all magic in stories is the same sort of thing, and it is all witchcraft. But that isnt the case, often it stands in for something quite different, and even witchcraft in a story may have little or no resemblance to the sort of thing Christians ought to worry about.