Well, I'm one of the few people who want to get this book, and it seems that a lot of things were left unresolved at the end of book five. Like what's behind the veil? What's important about the mirror Harry got from Sirius? Who will Hermione be paired up with: Harry or Ron? Or someone else? What will happen with Luna Lovegood, or Neville, or the Weasley twins' store? etc.
Out of the first five books, I think I like the third one the best.
The first one was good, but seemed like just an introduction to the whole wizarding world.
The second one I didn't really like that much, and I don't see much relevance of what happened in the book to the rest of the series, besides making it clear the Ginny could supply the information of what it was like to be possessed by Voldemort.
The third one I liked because of the Hippogriff, the time-travelling thing, Lupin as the Dark Arts teacher, and the idea of boggarts in general.
The fourth one was really good too, especially with the appearance of a dragon. I didn't like how it left things unsettled at the end, what with a student dying and just the beginning of the return of you-know-who.
The second I liked probably as much as the third. I really liked the Luna Lovegood character, and I also liked how the author was able to make so much bad stuff happen to Harry, yet he prevails in the end. Plus it's the nesest installment, at least for the next seventeen days or so, before HPatHBP!
Thank you for visting my world, come again ... Now entering reality, welcome back.