I thought it was a good rendition of the scope and feel of the book. Though many of the scenes were necessarily a bit truncated, the big set pieces were retained and the logic and flow of the story came through. The casting was excellent, I can't praise the actors enough. The special effects are important, and I thought they were almost always good. When I'm watching children's films I find myself hankering for a level of toughness that can't be there, but this pushed itself pretty hard against the limits of what young children can watch.
There was one scene, which I think shows the director/writer Chris Weitz gets it, and that Nicole Kidman can convey it. Mrs Coulter is alone with her daemon, her soul. It says something that offends her and in a shocking act she strikes it across the face, knocking it to the floor and then clutches it to her, sobbing 'You mean more to me than anything'. What a brilliant way to convey the deep sickness she has inside herself.
Kidman = compellingly evil, Lyra=excellent (the other children, merely passable). Daniel Craig = hardly in it, but what charisma. Derek Jacobi = impressive as ever, which is saying a lot. McKellen as the bear = as impressive as a big huge bear that can kill you. Eva green as Serafina Pekkala is almost perfect. It's all good, to be honest. Harry-Potter levels of grow-up actor commitment and quality.
My favourite character in the books - a fictional character I am in love with really - is Lee Scoresby. He is brilliantly, brilliantly conveyed by Sam Elliott. As The Big Lebowski said to him 'I like your style man, you've got that whole cowboy thing going on.' Adored him in every moment of screen time.
With all these characters, and with physical object and places (except Serafina) I didn't imagine them as the film portrays them, but this didn't spoil it for me.
When I got back from the film my daughter (who hadn't been able to come) asked straight away 'What did they do about religion mum?'. She was worried that they would tone down the conflict between spiritual freedom and religious authority(*), which we both think is central to the book. I think this is the most important question we ask ourselves going into this film - does it pull its punches to placate the American market?
My strong opinion is that they have compromised on the use of religious iconography - there are no recognisable trappings of any religion, even down to the architectural choices, in the way the Magesterium is conveyed. But I would say the underlying message of the trilogy - that the spirit is untamed and accessible by anyone, and that any attempt to punish it and dominate it will kill it - comes through with almost painful emotional force.
For this reason I was slightly disappointed by only one scene - where Lyra finds Billy Costa, stripped of his soul, dying in a frozen shed. This could have been as powerful as a Japanese child-horror film, like Ringu. This punch was definitely pulled. But what the heck, there were eight year olds in the audience.
One other mild disappointment I'll mention. The daemon's are variable, and unfortunately the first one we see (Asriel's tiger) is one of the worst. Don't let your heart sink too much when you see its unconvincing face, most of the others are better.
*ETA - I'm doing her an injustice here. For one thing she is 15 so she wouldn't put it in these terms; she just has this hard core militancy to her, quite a bit different from my views