Rotten Tomatoes‘ Consensus:
“It’s not easy to take the longest Harry Potter book and streamline it into the shortest HP movie, but director David Yates does a bang up job of it, creating an Order of the Phoenix that’s entertaining and action-packed.”
Order of the Phoenix was the longest book in the series. To expect a fully engrossed and complacent film from this novel was anticipating the near-impossible. Although Order does a good job not screwing up the entire Harry Potter franchise, it still falls well short of the mark, and in all is the weakest film in the series.
The film does have many positives to it. The inclusion of Dolores Umbridge is handled perfectly, as is the invasion on the Ministry of Magic at the end. There is enough in this film to keep the fans of the film series interested and locked into the film.
The issue with Order is the same thing that happens when you over-squeeze a roll of toothpaste. You still get what you want on the toothbrush, but not without losing the rest of the contents of the tube. A 900+ page book is damn difficult to transcend into a two and a half hour long film. It was an uphill climb for David Yates in his first go at the helm for Harry Potter, but he did a good job not tearing the foundation down.