In comparing it to the book, I can honestly say that it's as good, if not a slightly better experience. It tightens up the plot some, better explains some parts that were vague and visually creates the work in a way that the book couldn't. In addition to all that, it was wonderfully directly, fantastically shot, and had superb acting by everyone. The movie had no glaring weak points anywhere.
Seeing it in the theater on opening night was without a doubt the best way to have seen it. The showing we went to was about 1am in the morning and the theater was packed, the lobby buzzing with lines 20 people deep to all the concessions. Death Eaters, Gryffindors, and house elves wandered around everywhere. The HP passion was thick in the air and every scene was felt to the heart by everyone. It short, it was a wonderful show.