First I must point out that before I saw this film I had already read, and hugely enjoyed, the original book, so I approached this film with a mixture of high hopes as well as concern about how Hollywood would treat Philip Pullman's work. To my relief, I can report that the transition to the big screen was, give or take a few compromises, a success.
The 'alternative Earth' world that Philip Pullman has superbly conceptualised is visually re-created in this film very convincingly. The weirdly futuristic yet slightly Victorian technology is conveyed very well via some impressive CG-enhanced cinematography and the daemons that accompany every human are also very realistic and show that no expense has been spared in reproducing this strange world. The cast is also top notch. Daniel Craig makes a great Lord Asriel, mixing authority and intelligence with a subtle charm. Nicole Kidman is also wonderful playing the sinister Mrs Coulter, flicking effortlessly between affability and damn right scariness. The exiled bear prince Iorek Byrnison is also very well portrayed, the CG rendering is top notch and, being voiced over by Ian McKellen, gives the character the right amount of gravitas.
Where the film works well is that it makes Pullman's story very accessible to anyone who hasn't read the book. In his book Pullman crams in an incredible amount of ideas, some of which are quite mysterious and don't get fully explained until later on in the book. Therefore the film makers chose to simplify some of these intricacies to make them more 'movie friendly'. So, for instance, the whole concept of what a daemon is gets explained very early on in the film so the viewer doesn't sit wondering why everyone walks around with their own talking animal. This is in contrast to the book, where deamons just exist, no simple explanation is given as to why people have these animals, and it's only through reading the whole book that you begin to understand the mysteries of these enigmatic creatures.
I know many Pullman fans have criticised the film's simplification of many of Pullman's ideas as dumbing down, but I think this is a little unfair. Without doubt some of the more involved subplots are only touched on in this film, giving the impression that some of it was a little rushed as the film makers tried to cram as much of the book as they could into a 2 hour film. For instance, the Bear King's infatuation with being human, as well as his usurping of Iorek, has far more significance and depth in the book than it does in this film. Also, in the film, the role of the Witches is quite understated and they're portrayed almost like 'guns for hire' to help Lyra and the Gyptians when needed. In the book, however, they have a very profound involvement in the story and very much hold the balance of power in the unfolding events.
But the biggest compromise is without doubt the point at which the film ends. I will not give anything away, other than to say the film ends at about three quarters of the way through the book. So the film gets denied the book's original climactic ending, and kind of just fizzles out. It really isn't a proper ending and I feel this definitely could have been handled better.
But generally the compromises do not detract from the fact that this film is very enjoyable and a great introduction to the fascinating world that Phillip Pullman has created. Admittedly this adaptation isn't perfect and many of the book's subtleties and intricacies have been lost. But as a fan of the book I'm just pleased such a wonderful story has been given the Hollywood treatment and allowed a whole new audience to discover its delights.