Interesting, I hadn't heard that before. Still, for people learning Japanese, I tend to think it's a good choice. At my level, it's easy to get lost when reading things that I don't already know the general plot for. Harry Potter is pretty easy to follow and not too difficult from a vocabulary perspective.
Harry Potter is notorious among Japanese readers for having a horribly inaccurate translation. Example: http://islaya.sarashi.com/haripota01.html