It was...surreal. They used many, although not all, of the songs from the musical, Anna and the King (and their costumes) were modeled after Deborah Kerr and Yule Brynner and their costumes and there were many points of similarity between the plots.
However, I've seen the movie many times, and the stage play once (performed, I must say, by my brother's third grade class) and it seems that I missed a few things.
1. Apparently, there was an evil magician and his sidekick (who was rather obsessed by his teeth, all of which fell out by the end of the movie) trying to depose the king. I missed this subplot entirely, and truthfully, until the end it barely meshed with the plot I do remember.
2. Siamese servants were forbidden to read books.
3. When Tuptim (the pretty Burmese concubine) was introduced, her major talent was, apparently, flower arranging. Yes, that's it. Flower arranging. And she was a servant, not a concubine. And if she gets sent back to Burma, she will die. And she was in love with, not a palace guard, but the crown prince.
4. The crown prince was not a young boy, but a young man.
5. When one is attacked by magical fiery sea serpents, it's appropriate to "Whistle a Happy Tune."
6. I missed the baby elephant entirely.
7. And that entire rescuse sequence with the king and the prince and the girl and the stearable hot-air balloon over the fiery river of non-death.
8. Plus, of course, we only imagined the king dying. This is important.