I just finished reading it again years later, and I still don't get it. Hemingway's writing is always better than good, but it seems he used his powers here to tell a completely pointless story.
The characters are not good people, but they're also not explicitly bad people. They don't learn anything or grow in any way, and the entire book simply has them traveling around, drinking and eating.
I don't know if there is some larger comment on the human condition here, but it really feels like nothing at all is happening, and everyone ends right where they started, character-wise. Nothing is really gained and nothing is really lost, and I don't understand the immense praise this work has been given over the decades.
I still like to read Hemingway, for he is one of the few "classic" authors that are still easy to understand and relate to (unlike more complicated or literary authors like Joyce or Twain), and his influence on nearly all modern story telling is undeniable, but I really don't get this book.