Remember that unlike "Lord of the Rings" these were written for children and emphasize a child's sensibilities. "Always winter but never Christmas" exemplifies this difference. What could "Christmas" possibly mean to Narnians? Nothing, but it speaks concisely to a child's heart. If you are expecting "Lord of the Rings" you will cringe when Father Christmas shows up in a sleigh with reindeer, but that is in the book. One of the lead characters is a talking beaver, after all.
All this to say, the movie is faithful to the book in both content and tone, and the depiction of atoning sacrifice is clear. Aslan does not fly (as he does in the book) which is probably a good thing. He sounds like Liam Neeson which is OK, but a less recognizable voice may have been better. The talking animals were spotty: the beavers worked, the fox and wolves not as well. This probably has as much to do with the physical structure of beaver and canine skulls and jaws as with the animators' prowess; beaver faces are more human in proportion so their mouths can more convincingly mimic human speech.
The battle scenes also work. The gore of the Middle Earth battles is absent, as it should be in a children's movie, yet the scenes are well choreographed and engaging. The final battle between Jadis and Peter is especially well done, and demonstrates the cold masterfulness of the queen.
Overall, I predict success and sequels. If anything, this movie is more faithful to Lewis' book than Jackson's to Tolkein's.