Found this movie to be quite good. I enjoyed Macbeth (directors film before this). The set pieces were great, lighting and mood was great. last 25 minutes felt like it was cut up to reduce duration or was rushed in editing to get the movie out for release. Pleasantly surprised at lack of modern rap/rock music in the film. I feel as though the film received bad reception from the fans of the games due to being too creative and too much like a real film where as the people who are not from the video game crowd were dismissive due to the stigma of 'video game movie'. All the scenes in Spain were wonderful, especially the great set piece of the execution scene.
I have never played an Assassin's Creed game.