Ben Witherington has written an interesting appreciation of this classic story.
The story is at once a beautiful romantic story about true self-sacrificial love, and also a Christmas story, which talks about gift giving, in the tradition of the Magi. If you would like to read the precis of the story you can find it at this link which you can cut and paste into your browser. http://www.online-literature.com/o_henry/1014/.
What I like best about this Christmas story is not merely that it is free from the materialism and narcissism that so plagues the Christmas season of our era but also that it reminds us of a simpler time in our country where there could be an innocence and self-sacrificial quality to a romantic story without it being a fairy tale. Indeed, I could tell you a story very much like it from my own family. In the meantime, if you are looking for a Christmas story to read your children, forget about Grinches that steal Christmas or Scrooges that sour it, and go for this one which shows how to keep Christmas....or give it away.