Well, I HAVE read the book, and I can say you are right, the storytelling hangs together far better in the book than in the movie. It is true that much is left to be explained in the second and third books, but the characters and their actions have much greater depth and coherence in the books, mostly because the movie goes through the events in such a rush that one hardly gets a sense of what is going on, or why.
Even so, the movie ends well before the place where book one ends, and thus we miss the culmination of Lord Asriel's plan to bridge the gap between worlds. (Lord Asriel himself is a far more interesting and morally ambiguous character in the books; for example, his scheme to go to other worlds requires him to murder a young child in cold blood). Serafina Pekkala, a pivotal character, barely has any lines in the movie. As a resultof all this, characters end up spending much of their meager speaking parts spouting exposition. Further, the script is too chicken to allow the audience to figure things out, so we get even more exposition to explain things like the relationship of people to their daemons which the book simply takes as a given and expects readers to keep up.
The production IS sumptuous, and Dakota Blue Richards does very well with her character. But the film ends up seeming more like the edited highlights of a movie rather than the movie itself. A shame, as the story in good enough to deserve a less rushed telling.