I'm by no means a vegetarian. I realized animals are slaughtered every day to provide food for humans. But there is a marked difference between quickly and painlessly killing a cow (which is done by instantly deadening its brain)... and hunting down and slowly "executing" a whale. Not only are whales far more intelligent than cows, the pain they go through in the whaling process is nothing short of torture, beyond butchery. Many won't be able to enjoy this anime because it will make them sick to their stomach. It's very difficult to identify with a crew of people who seeming take enjoyment out of slowly executing what some would consider a magnificent creature. In short, this anime is too predictably offensive to earn a good rating. I'm actually surprised that anyone gives his an 8-10 star rating... and that we don't see more under-5 ratings based on thematic issues alone.
Anime should not be judged purely by the graphics and characters. Story and theme is equally important.