I saw the movie yesterday from the front row and felt completely absorbed in the action.
Like others have said, it's not completely true to the book, but some decisions had to be made for the movie to be as short as it was. To be honest, it was over before I realized it; so much was happening.
As for the cliffhanger ending, that's also part of the story in the book, and I thought that was handled well.
My 10-year old daughter really wanted to see this movie. She says it's better than the first one. I wasn't as familiar with this story as the first one, but it was very enjoyable. The action at times was intense. Those interested in the spiritual themes will not be disappointed. As we left the theater, we felt we could relate to the Pevensie children in that we had to leave the magic of the theater experience, just as they had to leave Narnia. Definitely recommend seeing it, in the theater if possible.