Today the DrsC attended a matinee performance of Harry Potter and the Order of the Phoenix, or OotP as the fan sites call it. In a word, it is "excellent."
Book five is not our favorite among the Potter oeuvre, because much of it is downbeat. By shortening the story of year five, the movie actually improves the telling of that year, while sacrificing relatively little that is crucial to the overall story trajectory.
The film leaves out Harry's disastrous date with Cho at Madame Puddyfoot's Tea Shoppe in Hogsmead. Rowling's description of this misadventure is enough to make any man who remembers his own adolescence cringe. At the end of the day, however, that scene does nothing to move forward the basic plot line: the battle with Voldemort.
The film also leaves out all mentions of Quiddich: the episode of Harry being banned "for life" from playing Quiddich as well as Ron's struggles to overcome lack of self-confidence as keeper while listening to the Slitherins taunt "Weasley is Our King." Likewise gone are the visit to St. Mungo's Hospital and Harry's interview in the Quibbler. These add to the great length of the book and are surely fun to read, but their absence does not detract from the film.
The casting of Umbridge is odd. The book describes Umbridge as toad-like and repulsive in appearance whereas the actress cast is nice-looking. However her character is the classic bureaucratic tyrant and she plays it well. The casting of Bellatrix Lestrange is also interesting, again the actress selected doesn't look much like the character described by Rowling.
This series has suffered other episodes of odd casting, most notably the casting of Fleur delaCour, the Beauxbatons champion who the book claims is a haughty part-Veela and drop-dead gorgeous. The young actress chosen to play Fleur in film four - the Goblet of Fire - is pleasant-looking and French but certainly no great beauty. They needed a young Catherine Deneuve and got instead the girl next door in Paris.
On the other hand, the casting of the Luna Lovegood part is excellent, as is the actress who plays Tonks. Both of these are new to the series and great additions.
If you like Potter, you will like the film. Yes, much had to be left out and you can quibble with what stayed and what went, but what stayed is very good indeed.