A great movie with a great plot. Indeed one of the best movies I have ever seen. You could see other reviews in here criticizing it not to meet their expectations. They tend to compare such a classic with other sci-fi or fantasy type movies to put forward a verdict. I believe this remains at the top spot all these years for a specific reason and that reason being that such a classic hadn't been created all along and the same would be a difficult one to achieve. Unlike today's commercial films which aims purely on box office hence the audience, this movie, as an oldie, concentrates on it's plot.
The movie, set in the 19s, is basically about a banker convicted of murder, his life in prison and the rest following. Its a classical masterpiece. It is basically a rollercoaster of emotions where you experience everything from happiness to sadness.
Coming forth, the movie is what you want if you like a great plot, a good twist, a good package of emotions and a good message for life. It may not attract you if you want a "super" hero who kicks some butts, a love story, a cool protagonist, a feminine power, a mystery thriller, a crime investigator, a fantasy or anything today's majority kids find cool.
I highly suggest you to watch this movie because it would be a great loss if you don't.