It's been several years since I've reread this one (maybe seven?). It seems more polished and put together than most of the other Narnia books. This one was the last Narnia book Lewis finished writing (according to wikipedia) and I wonder if that made a difference.
This has been one of my favorite books ever since my first grade teacher read it to us in class. In this book the time spent in our world is pretty balanced with the time spent in magical worlds (so it's the opposite of The Horse and His Boy), which I think is part of why it's my favorite. It's the closest to low fantasy that this high fantasy series gets.