I have finished the book, less than 24 hours after its release. And yes, I know there are people out there who hate people like me for it. 
I agree very much with the previous review. The book, along with the previous ones, speaks very much to the maturing reader. It is as if Rowling has deliberately written each book in the series for the temperament, and for the problems, of the readers Harry’s age, as Harry progresses through school.
The other aspect of this book that I found most intriguing was the recurrence of numerous lovable details from previous books, and generally assumes the reader is familiar with them. If you liked the creative elements and characters from the previous books, many of them resurface here.
It also answers a lot of questions not entirely covered in previous books. Gaps are filled in. Principal characters are fleshed out and given a better history. A couple of new characters in particular are enjoyable. (Enjoyably nice, or enjoyably bad: but enjoyable.)
It is much grimmer. (Grimoire?) It is much more grim. (Better.) For re-readability, I can’t say yet. It hasn’t sunk in.
If I were to rate it, it’s probably closest to Goblet of Fire in that it deals with adult issues, including the pressure of notoriety and the difficulty of being misunderstood, and Harry’s attempts to deal with the opposite sex at Hogwarts. It’s probably most like Chamber of Secrets in the tantalizing clues of the main plot, something just below the surface that Harry doesn’t understand. And it’s got flavors of Prisoner of Azkaban in it, mostly in the backstories of Harry’s father (and James’ friends and enemies).
Tough to say, though. I laughed out loud several times toward the end of the book, and I have to admit I read the thing solidly from five until midnight, turning page after page.
I got my copy at the supermarket. No lines.
FISH