I'm a long time fan of the books, having read them probably around four times over since I first got my hands on them around five years ago. I must say I was really disappointed in the film, I thought the directing was bad, the storyline was flimsy, and the heart was sucked out of it.
I agree that Ian McKellen did a fantastic job as Iorek - as a matter of fact I thought most of the casting was excellent. But that was all. Not to mention they took out the entire ending of the book for "story reasons", which was basically done to soothe an already confused test audience. That and they changed the name of my favourite character, Iofur, because they thought his name was too like Iorek, and goodness knows people simply couldn't handle that.
It was a shame Peter Jackson wasn't a Golden Compass fan, or some other decent director.