I saw the movie several years ago on TV. I couldn't really remember it now, but I did like it, and have wanted to read the book several times ever since. I've been running about a lot nowadays, and I love listening to audiobooks. I have had the audiobooks for quite some time, and this was the perfect opportunity to listen to them, so I did. Once I was done with the first book, a rewatch of the movie was in order.
This movie didn't do well in the box office. Some blame it on the religious theme of the story, others on it not being a very good movie. I quite liked it, though now that I know what they worked from, I can see the problems. For a discussion on the story itself, please read my book review.
The story didn't change much. They did merge a few characters, as it sometimes happens. What was strange was the introduction of the councillors and the Magisterial Emissary. It is remarked in the books that the Magisterium dictates a lot of things, and is half supporting Mrs Coulter, but it is her eagerness for power, which drives the negative events, not the Magisterium, as it appears in the movie. Or so it was my understanding as I read the book. I did wonder why they made it out so, but I couldn't see any justification for it. Maybe more will be revealed int he following books.
Another change as opposed to the book was the revelation of Lyra's parents. In the book, Lyra learns about it under very different circumstances, and much sooner. I think they placed it so in the movie, because it had a bigger impact on Lyra that way, but it didn't seem to matter for the story all that much.
The third big change was the order of the last couple of events, and especially leaving out the last big event. Lyra coming across the children and the bears is the opposite in the book. The only reason I can see for the change is that in the movie the party at Mrs Coulter's house is left out. It is there that Lyra learns of Lord Asriel's imprisonment among the bears, and that's why after the children she goes there. While in the movie she knows nothing about that turn of events, so she would have no motivation to head that way, and therefore has to just happen on that storyline while heading to her original goal.
The fourth big change is that they left out death, that seems to be an important part of the story. From Lyra exploring the catacombs in the beginning, to the end, death is a part of the story. In the movie, it was taken out. Sure, characters die, but not children. We know from the books that the poor boy Lyra finds dies, and yes, I did shed a tear, but that's not clear in the movie. That particular horror is left out, making the tone milder. In a way, the children who die make what is really happening - without giving too much away -, all the worse. That people would do that without a thought, just to keep children from growing up to thinking freely.
The biggest change of all is the milder tone overall that the movie takes. Gone are the references to Christianity. The Magisterium is the big bad, the organisation, while in the book, it was the underlying doctrine, that is the actual problem. I can understand the reason for the change, even though I wasn't pleased by it. The milder tone was also achieved by the ending. Since in the book, Lyra does reach her final end-goal, and in the movie she doesn't. I can especially understand this change, since that still haunts me a bit, and I'm somewhat glad to not have seen it.
The best thing about the movie is really Nicole Kidman. She was picked and persuaded by Philip Pullman himself to play Mrs Coulter. Sure, her hair is blonde, but even the author admitted that he should have described his character as a blonde. Nicole Kidman is perfect for the role. Cold, ruthless, even when trying to care. I'm not a big fan of hers, I think in some things she was terrible. However, I will always see Mrs Coulter as she portrayed her.
The second books was never made into a movie. It can be the problems with the anti-religious tone, or the fact that a lot of people didn't like it. Truth be told, it did feel rushed. All the events were crammed into these 113 minutes, clearly not enough. However, back in 2007 TV shows still didn't have the budget they do now. 2008 did one good thing. TV became more important, as people cut back on going out. Shows became more popular, and therefore more money is poured into them now. This book would have clearly worked better as a TV show. That is what will hopefully happen, as BBC has promised to develop the trilogy as a TV show. I'm sure the books will the in good hands, as BBC adaptations are very high quality, especially in recent years.
Overall, watch this movie. It's pretty good on its own, and if you're unsure about reading the book, it will give you a general idea of it. The CGI is also terrific, and don't forget the real highlight of the movie, Nicole Kidman as Mrs Coulter.