Actually, the "cliffhanger" ending is evidence of how little faith New Line had in the movie. The book goes on for another chapter or two after the movie's ending point, and the book (real) ending is a much more compelling cliffhanger. I really don't know why they would decide to cut it off early... other than to provide a more palatable stopping point should they decide not to make the next two movies. (They actually filmed the real ending too, but decided to cut it out. Ugh!)
As a huge fan of the books (volumes two and three in particular), I have to say the movie overall was rather meh. They rushed much of the plot/relationships development and glossed over a lot of the deeper points. Actually, since they neglected to explore certain elements of the story in depth, and because the first book lays so much groundwork for what happens in books two and three, I think it would be very difficult to do a good job on the next two movies at this point. It's really a shame.
BUT it was nice seeing everything "come to life," so to say. Really loved Dakota Blue Richards as Lyra and Nicole Kidman as Mrs. Coulter. All the other actors were great with the few lines that they had. Though Ian McKellen as the voice of Iorek was a little bizarre. They pretty much changed the bear's personality completely. He's supposed to be a cynical and weathered kind of character, and I think the movie shows him a little too good-natured and readily subservient to Lyra. At least they redeemed him with a badass bearfight.
Speaking of which, why didn't they explain the underlying reason for Iorek's win? It would've taken all of maybe two minutes of footage, and it's a lot more interesting than the "oh, he won through strength of heart" thing that we ended up with. Anyway, point being, there were so many places where they could've sneaked in just a little more depth. A lot of missed opportunities here, and I can't help but think New Line has only screwed itself over with this one.