I like it that she (Rowling) left me with a couple of "I wonder..."s at the end of the last book. I was really pleased to see the transition in Dudley, though--that was a nice touch.

I try to do the same thing anytime a new book comes out in a series that I like. I re-read the entire series prior to buying the newest book. Sometimes it just isn't possible (too many books to go back and re-read) but I always enjoyed doing it for all the Harry Potter books. It's one of the things that makes the series so good, in my opinion--that I can go back and re-read it over and over and not get bored. I find little things I "missed" all the time.