The most current of the series, Book 5 is also the longest & most complex of the Harry Potter books, really emphasizing relationships outside of Hogwarts almost more than inside the school itself. I re-read this book very quickly (maybe 3 or 4 days, which I know is not as fast as some of the 10-year-olds I know read it when it came out) — I find that the books get a healthy momentum going and you really just want to see how things turn out.
I don’t think that I like this book as much as the 4th book — and I think it’s probably a little too long, really, but still really enjoyable, and you can start to see the outlines of what’s going to happen in the final two books in the series. Definitely looking forward to the new installment in July.