I liked the Harry Potter books pretty well, read them with my daughter and found them charming. I didn't see the delineation as blurred at all in them, just see the books as generally more lightweight in every way than LOTR. In spite of all the (I think unwarrented) controversy about them, I see them as a good influence on kids, unlike, say, most TV or Hollywood stuff.
But I'm glad that LOTR is our book.
I've read all four and I have to say I'm glad my kids are old enough that I don't have to make a decision re: whether to allow them to read the books; "Goblet of Fire" in particular I thought was very dark, for younger children in particular. PERSONALLY, I liked them; found them to be witty & clever & a marvelous escape. But I do understand some of the concerns of others. And I agree; glad LOTR is what we're about here.:^)