It's a Wretched Hive and most of its population are chem dealers, or homeless drifters. Though similarly to the Followers of the Apocalypse having a presence in Freeside, the Railroad's generally benign (if rather discreet) presence helps as well. However, Goodneighbor is also far more formidable than Underworld and is fiercely independent, whereas Underworld's fate is still unknown (with it being implied that the BoS lynched the city/encouraged its residents to move somewhere else).
Foil: The city as a whole is one to both Underworld from the Capital Wasteland and the Mojave's Freeside.
Despite being ostensibly under Hancock's control, the city is largely a state of anarchy, but seems to take care of itself well enough.
