I’m probably not representative of the target audience for this movie. I only read the first book in the Harry Potter series, though I have seen and enjoyed all of the earlier movies. I suspect that most of the audience went into the movie having already read (and perhaps memorized) the book it is based on.
Thus I have no way of knowing whether flaws in the move are due to flaws in the book, or are the fault of the director. Part of the problem may be due to the fact that it is a very thick book. The movie feels like too much material has been crammed into too little time. Plot points are checked off rather than developed and key events rush by almost unnoticed.
If you have not read the books or seen the earlier movies you should not start with this one. A newbie is going to have no idea who these people are, what the hell is going on, or why anyone should care. Even though I had seen the earlier movies it was as struggle at times to figure these things out.
Every so often we see glimpses of the invention and whimsy that the series is famous for, but many of the elements that made the earlier movies so delightful are missing from this one. There are no Quidditch games. Hogwarts becomes a grim and unpleasant place. Even the customary celebratory end-of-term feast is not shown (though apparently it takes place.) Harry Potter himself spends much of the movie wallowing in angst and impotent rage. Indeed the hero has never seemed less likable.
There are good reasons for much of this. The story is mostly about Harry’s struggle with his own dark side. But psychological challenges are difficult to portray in a movie; much harder than physical threats. The movie’s climax is a spectacular special-effects extravaganza, but the psychological elements of the struggle are never very convincing.
Aside from Harry, the movie has little time to spend on character development. This is particularly missed in the case of two new characters (one of whom appeared briefly in the previous movie.) They are apparently supposed to be important, but they remain mere ciphers.
All in all, this movie is best justified as a bridge between the previous movie and the next one in the series, which I hope will be better.
That said, I am going to go out on a limb and make a prediction about the end of the series. A number of people who have read all the books and know far more about the series than I do have assured me that Hermione is going to end up with Ron Weasely, and Harry will end up with someone else. I think otherwise. Hermione is the only female character anywhere near Harry’s age who is at all interesting. Obviously she is intended for the hero.
Right now Hermione is the female buddy that Harry has no romantic interest in. But it’s fairly standard for a hero to wake up and realize that the woman he loves has been right in front of him all along. Furthermore there are plenty of hints in the movies that Hermione is interested in Harry; she just isn’t obvious about it.
(Of course if the last book ends with Harry’s death then all bets are off.)