The Underworld is often a gloomy, depressing realm, if only because it is often depicted as being Beneath the Earth. (The fact that people go there after they die might have something to do with it, too.) Still, it isn't evil. It's not Hell. All of the dead come here, whether they were saints, total jackasses, or just kinda so-so in life. Some versions of the Underworld judge the dead and grant them different living standards (or unliving standards, if you prefer) depending on their conduct in.