I'm just about finished reading the new Harry Potter book for the second time, and before I go any further I'd like to point out that I liked it enough to have read it twice within two weeks of release
I can't help feeling this is the first Potter book which isn't 'stand alone' - that is, there's not really enough plot in the book to keep someone reading if they didn't care overly about the major revelations going on every other chapter (ie. someone reading their first HP book). It seemed to me a bit more like "Here's all the things you're going to need to know before the final book" with a few chapters of action tacked on at the end.