I like letterboxd, but unless I read through all the comments, I can't make out if I would like a movie or not. There scoring is similar to imdb. I dont think just a simple rating system would be a solution.
The most efficient solution is to give the user a predicted rating which tells him at first glance how much he'll like a movie. Of course the prediction is based on how much the user has liked other movies (collaborative filtering). Netflix used to do that quite well until their recommendation system went down the drain for marketing reasons. My app Coollector Movie Database works on that principle.
