The Cloverfield Question

All of the criticism for JJ Abrams upcoming film Cloverfield is based on the fact that nobody knows what the movie is actually about. The Question though is if that is actually a bad thing? Do people really want to know the entire plot line of the film before seeing it, or would they rather be surprised. We already know that it is a monster movies directed by one of the best in the industry. What more do you really need to know? If you want to see a monster movie or what not, you can go ahead and see the film, and watch it for yourself to find out the details. I actually hate it when they give away a major plot detail in previews, because then you spend have the movie just waiting for the scene you already saw to happen. I really don't see how not knowing the plot to the movie before seeing it is a bad thing...