The Harry Potter books fall into the genre of youth fantasy. In several respects I would characterize them as fairytale in style, moreso than modern fantasy literature.

If fantasy literature and fairytales are inherently bad, then the Harry Potter books are bad for that reason, along with the books of J. R. R. Tolkien, C. S. Lewis, and scores of others, the Star Wars movies, and a whole plethora of fantasy and science fiction entertainment. The Potter books themselves are not overtly worthy of condemnation for their story line, they certainly don't teach sorcerer or advocate New Age thinking at all. The handling of wizardry and so forth is not intended to be in any way believable or realistic, and in the places where the books deal with topics of real world "magic" such as fortune telling, they generally ridicule it. The writer does not deal with religion at all (at least in the first four books) which is not surprising, being British (a much more secular society even than America), but along with not depicting religion in a positive way, she also doesn't denigrate it or cast religious people as fanatics, as some fantasy writers do.

The books are tremendously popular because #1 they are well written and #2 they deal with things that people like and feel good about. They have strong themes of true friendship, self-sacrifice, loyalty and struggle against difficult odds. There is a powerful depiction of the weak overcoming the mighty, the underdog surviving and going on to victory, and many people not only can identify with it, they are hungry for it.

There are ghosts and dragons and giants and witches and so forth, as in fairy tales. There is no blurring of the conflict between good and evil, or that there are real distinctions between good and evil. There is much that is good in the books.

Of course the main reason the Potter books have come under such scrutiny is that they are very popular. Again, I believe that the only way to reasonably condemn the Potter books is to condemn all fantasy and fairytale entertainment. I know brethren who take that position, and I respect those who are consistent about it. I take the position that there is bad fantasy literature (and movies, etc.) with very destructive themes which should be avoided, and that overindulgence in any form of entertainment will produce problems, but the genre is not inherently bad, and the Potter books are among the better examples of modern fairytales, so far.