Bruce Robinson's adaptation is wholly unimpressive. If you haven't actually been to a movie in which you were actively checking the time but seeing one is one of your life's goals, then The Rum Diary is the movie for you. The verve that is supposed to be there is absent. The sexuality that Chenault (Amber Heard) is supposed to ooze is there but is not nearly as amped up as in the book. Johnny Depp is basically just doing a toned down version of what he had already done in Fear and Loathing in Las Vegas, only with less drugs and a much safer vision.
Look, I like Withnail and I as much as the next guy, but I don't think Bruce Robinson would ever put himself in the same directorial conversation as Terry Gilliam. This film simply isn't good enough to warrant going into more detail.
In short, The Rum Diary is interminable and lackluster. Those are not adjectives that get people out to the theaters.