This was the first time I saw a Harry Potter movie after reading the book. The 1st 5 I did the movie first, then the book. I think that is the way to go. It allows you to love the movie and then be blown away by the book.
Having said that, I still really enjoyed this movie and they did a good job setting us up for the last book (two movies?). I could have used a few more background scenes from the book on Tom Riddle (especially about his family and the ring).
Overall, a good movie experience. Can't wait for the next one.