Agatha Christie is rightfully known as one of the best mystery writers. I've slowly been working my way through her books.
I knew the plot and the basic resolution going into this since I saw a play based off the book years ago. I didn't remember many specifics and had fun learning about the different characters. One interesting thing was that the play did have a different ending to the book.
If I remember correctly, and to be fair I may not it was many years ago, I remembered that the final two were a young man and woman, and the woman shot the man, but then the judge revealed that he wasn't dead and tried to kill the woman. I forget what his exact plan was. I think she did actually kill him and survive. However in the book, she kills herself and we find out what happens through a letter that the murderer left and threw into the ocean. So it was nice to still be surprised when I thought I knew what would happen.
(show spoiler)
Doesn't beat Murder on the Orient Express though.