This was a fun read. It filled in the gap while I waited for books 5-7 to come out. It refers to the books in a way that it's just like you're re-reading the first 4 HP's. And you realize some of the little things that Jo was creative enough to include in earlier books that are then used in the later books and you see how many themes are repeated. It was all of these small things that made the series so much more enjoyable than it already was.
For books 1-4 only. There are interesting tidbits in here but most of it can go either way. I think the writers waited until the next book to make sure their predictions were accurate. I would have appreciated honesty and reasoning more. Lots of use of the word "may" and "maybe" but if there was reasoning and proof, I wouldn't have minded. Good resource for a school book club.