The only way I can really judge this for myself is by reading the book itself... And the way things are going, it doesn't look like that's going to happen anytime soon.
Quote:
"The Harry Potter Lexicon draws material and inspiration from the Harry Potter series but is an entirely new piece of work," said David S. Hammer, co-counsel for RDR Books. "It is a companion to Rowling’s work, not a substitute for it. No one is going to buy the Lexicon instead of a Harry Potter book, or instead of seeing a Harry Potter film."
I completely agree.