Trailers often misrepresent the overall spirit of a movie, in this case the trailer was far superior to the actual film.
Napoleon was visually striking, the costumes were incredible, the violence was visceral, but the pacing of the film was uneven and the plot lacked the depth and complexity of the character the movie sought to explore. There were large parts of the movie where characters seemed to languish in the scene, the writing doing nothing to move the story along. There was no real development of the world around the characters, no sinew to the film. Everything was happening in a vacuum. Napoleon had all the trappings of an incredible holiday epic: big budget, good acting, vivid cinematography, but the film proved to be an expensive, dark, and meandering flop.