They got it right. I hardly dared to hope it could be done, but they really did get it right. At least, all the parts I personally strongly felt they needed to get right, they did. And the bits they added in that weren't in the book, I mostly didn't mind, or even outright liked (like the fox).
The absolute best bit, though, has not been mentioned by anyone in any of the reviews I've read to date: When Aslan turns from killing the White Witch, and looks at Peter and says, "It is finished."
My eyes nearly popped out of my head. I couldn't keep it in -- I just burst out, "OH MAN THAT'S SO COOL." I'm sure half the theatre must have heard me. I mean, here I'd been afraid that they were going to downplay the Aslan-Christ parallel or somehow mess it up, and instead they went and made it even stronger, by having Aslan speak the very words of the Lord Himself. I had shivers, and tears in my eyes (not like I hadn't been crying ever since Aslan went to the Stone Table, mind you) -- it was beautiful. Perfect.
As for the rest, Tilda Swinton's White Witch was every bit as cold, ruthless, chilling and brilliant as she needed to be -- and the duel between her and Peter was, as I just finished saying to lydaclunas, WICKED COOL. Loved the way she used her wand and the sword together. As for the Pevensies, I've always had a bit of a literary crush on Peter, and I must say this movie did not discourage that at all. Susan was lovely, and I was very interested by the way they emphasized her being "logical" and more focused on practical and earthly realities, as it were, than the others -- maybe I was reading too much into the script, but they almost seemed to be hinting at her eventual loss of belief in Narnia. Which, I have said before and will say again, is a genuine tragedy and not a case of "Good riddance to bad rubbish" in the least, and I'm sure I will cry buckets if and when the movies get to that point.
Also, hee on the movie's revisionist handling of Father Christmas's infamous "battles are ugly when women fight" comment, rubbed in still further by the presence of tough-looking female centaurs in Peter's army. It's not like I was sentimentally attached to that line or anything, so I didn't mind that particular change in the least. In fact I got a bit of a chuckle out of it.
In short, I loved the movie and would gladly see it again, and when my kids are old enough not to be scared witless by some of the nastier-looking creatures, I'm sure I will. And in the meantime, there's Prince Caspian to look forward to -- at this rate, the sooner the better.
Note to self: badly need at least two Narnia icons.