If you have kids, chances are that you have seen this movie a bazillion times, and probably even ridden local Polar Express trains that pop up every Christmas. It is safe to say that out of any books on the list, this is one of the most widely (and shrewdly) marketed expansions from the original book.
While the book has a complete plot, the writers for the movie had to expand to make the story fit a feature length film. Therefore, if you have only ever seen the movie, you may find a lot missing from the book. However, the scriptwriters did do a very admirable job in keeping with the tone and feeling.
The main themes remain: how to be kind to others, to have courage, to respect leadership, the value of friendship, and simply how important it is to believe. Without the distraction of the sometimes weird CGI animation of the movie, the importance of these themes come through much clearer in the book.
Based on: The Polar Express, written and illustrated by Chris Van Allsburg (1985)
By the same author: Jumanji; The Garden of Abdul Gasazi
Also take a look at: Night Tree by Eve Bunting and illustrated by Ted Rand; The Wild Christmas Reindeer by Jan Brett