Although there have been a few adaptations of this, the gold standard is the 1966 cartoon narrated by Boris Karloff. Aside from the addition of the songs, it is nearly 100% faithful to the original book. (Actually, the lyrics to the songs were written by Dr. Seuss himself, so the argument could be made that it is 100% true to the original). One could also argue that this is another redemption story, not unlike A Christmas Carol. The Grinch and Scrooge do have an awful lot in common, and both are transformed by the magic of Christmas.
If you have only watched the movie with Jim Carrey, or the newer movie that just came out this season, then you definitely need to make sure that you read the book with the kids. Because the story will be familiar, it could be a great way to get a reluctant child to read. It could even become a cherished holiday tradition.
Based on: How the Grinch Stole Christmas, written by Theodore Geisel (aka Dr. Seuss) (1957)
By the same author: The Lorax; Horton Hears a Who!
Also take a look at: A Charlie Brown Christmas by Charles M. Schultz; Bear Stays Up for Christmas by Karma Wilson