I actually was lucky enough to see this at a sneak preview on Monday. The "experience" was lousy, but the film was good...IF you take it as a separate entity from the series of books. If you separate the film from the book, you won't be disappointed.
For the negative...there were, of course, MANY things that were omitted from the film. As a huge fan of the books, I still must be realistic. I knew there would be a lot of information left out. There were a few things that I felt could have made the story richer if they had been included, but I won't go into detail so I don't give away any of the film's changes. There were a few changes that made me frown at times, but as the story played out, it did make the film flow well. One of their worst casting decisions, Michael Gambon, was actually tolerable in this one, for the most part. I am NOT a fan of his portrayal of Dumbledore, but I guess he worked for this film simply because, for the majority of the story, he is supposed to be acting somewhat aloof towards Harry. That worked for him. I miss the subtlety that Richard Harris brought to that role, and, while he wasn't dreadful in this one, I still believe that there are countless other well known actors in the UK that could have done this role better justice. There wasn't enough Molly or Hagrid for me though. I love both of those characters.
On a positive note, the special effects were very well done. The thestrals were marvelous--eerie, but strangely peaceful creatures. Evanna Lynch could not have been more spot on as Luna. Her voice, mannerisms and demeanor were amazing. My only complaint about her was that she wasn't on screen enough. :o) Imelda Staunton, as Umbridge, and Helena Bonham Carter, as Bella, have to be two of the BEST casting decisions that they have with regard to these films. They were SO incredible. I was actually quite impressed with Dan, Rupert and Emma as well. They have come quite far in their acting abilities. They have finally achieved the art of saying a lot without necessarily opening their mouths. The scene in the common room following the kiss between Harry and Cho was hysterical. Kreacher and Grawp were great additions to the films. Fred and George's exit was very well done, albeit slightly different. The film, if taken by itself, was really good. Unfortunately, it's a lot different from the book. But, as I'm doing a film review and not a comparison, I'll give it 8 out of 10, because I was highly entertained.
Our "sneak preview" was interrupted in the middle due to a problem with the film, and I think we still missed some of it. We lined up 3 hours before the movie was supposed to begin, it started late, it was interrupted in the middle for over 30 minutes, we were wanded for metal and electronics every time we went in or out...I think we'll just wait until opening week next time. It's crowded, but a lot less trouble.
We are actually going to see it again.