I don't really want to compare this book with the movie too much namely because I am glad that they are turning these wonderful books into film and don't want to put anybody off seeing the movie. Personally I do hope that they do go on and make the rest of the books into movies, but with that said, the movie and the book do contrast with each other in that the movie is a lot more action orientated with a theme that holds it together, but while being different from the book, with new foes and a change in the order of the events, as well as a 'dumbing down' of the Christian allegories that exist throughout the book. Despite all of that I still found the film to be very enjoyable.
As for the story itself, it seems to be a cross between Homer's Odyssey and Pilgrim's Progress. Only two of the Pevenese children come on this adventure, but they bring along with them their annoying cousin Eustace Scrubbs, who is a scientifically minded boy that has no time for fantasy. This changes when he discovers the magic of Narnia, and this is what I believe Lewis is getting at with all of his Narnia books. By using the allegory of Narnia what he is doing is reintroducing the magic of Christianity into this world to help children, and by extension the adult readers, that there is still a lot of magic in this world that we tend to forget in our industrial age.
The other theme in this book is the voyage of discovery, which is why I would probably equate it more with Pilgrim's Progress rather than the Odyssey, whose theme is Odysseus' homecoming. However, there is a homecoming of sorts for Reepicheep, who has gone on the journey to find Aslan's country which is beyond the end of the world. As the journey continues, the characters grow, meet old friends, and come out of it understanding themselves better that before.