The problem with movies based on books is that they can never include everything that the book had, so it comes down to what is include and how important that is to the overall story. Michael Goldenberg is responsible for the screenplay in this fifth movie in the Harry Potter series and I must say that he has done a good job. My only concern is that this is probably the movie in the series with least ability to stand on its own since the story is heavily influenced by the previous books/films.
If you have like me watched the previous movies the Order of the Phoenix is a great addition to the family. Our main characters are now well in their teens and the story is a lot more serious and dark. The fantasy monsters and childish spells are replaced with a much more grown up atmosphere, things are becoming serious and dangerous. This is an evolution that is present in the book series and it is good to see that this is also the same for the film.
Our main cast are on top of the game again and I was also pleasantly surprised by the rest of the cast. It was nice to see more from Ginny Weasley (Bonnie Wright), Matthew Lewis (Neville Longbottom) and Gary Oldman (Sirius Black). Evanna Lynch is one of the newcomers starring as Luna Lovegood and she delivers a great role, but the best new actor is easily Imelda Staunton as the controlling Dolores Umbridge.
Responsible for music is this time Nicholas Hooper, but I was not that impressed. His score is not close to as good as John Williams' and I felt that it was lacking something. It doesn't have the right Harry Potter feeling to it that the previous films had. Special effects however are great and used in the right amount. The fireworks scene and the ending are great examples.
As the books become longer the movies get increasingly harder to make, but overall the Order of the Phoenix is a great addition to the series. It has some problems as an independent movie, but as a continuation of the story it works perfectly. The acting is top notch and most of the mandatory plot elements are included. At some point the viewer has to acknowledge that everything cannot be included and I was satisfied with the job that the team has done. 8/10