A lot of people know this story because of the movie adaptation. It's a very mysterious story from the beginning and it's intended to be that way, it's the official start of the Narnia universe, C. S. Lewis had thought of making a book about a Lion and created a masterpiece.
But coming from reading The Magician's Nephew some of the mystery dissipated by knowing how everything began and where it was that the heroes stumbled upon entering the wardrobe. I even know who the lion and the witch are!
This does not stop the story from being great. There are a good number of examples of good behaviors and bad ones. For example, if you have someone you love and they come to you yelling that they were in a forest and met a faun and it was winter, and it all happened while they were hiding in the wardrobe of the house, you should probably start worrying about their mental health but not before you wholeheartedly try to understand and believe that at the least, they did experience this.
Also, don't listen to a witch who gives delicious candy in a forest.
A group of brothers and sisters save the day by being brave and righteous, I'm feeling a little bit of a theme in these books. By a little bit I mean these are all Christian books and I love them.
The last thing I'll mention is how short the last battle is in the book as opposed to the movie. The Chronicles of Narnia is a story about the good triumphing above the bad, but most of all, a story about adventure.