The recent movie re-make of this classic triggered our interest in the book. My sons borrowed it from their school library. This is one of few books which we both read. I originally wanted us to first write down all the clues and then try to figure out together who the murder was. But I quickly got too absorbed into it and went all the way to the end. I finished it in two days, finding bits of time here and there to read it. I also realized that as a reader, one does not possess all the information to reach the right conclusion, so there is no point trying to figure out the answer on your own.
Overall, it is a classic for good reasons. Very well set up plots and colorful characters. The first chapter is a bit slow, but after that, your attention is always captured.