Nar Shaddaa is a vast metropolis, similar in scale to Coruscant orbiting its parent planet Nal Hutta. It features towering skyscrapers across the planet, covering its entire surface. While it is a massive city, its history is far different from the Republic counterpart.
When the Hutts evacuated their home planet of Varl and arrived on Nal Hutta, the native Evocii stood in their way. As a result, the Evocii were enslaved and forced to the nearby moon. Here they were forced to start construction of starports for this newly growing trade hub. Upon completion of their labor they were forced into the lower portions of the city, similar to the society of Taris prior to its destruction.
As trade routes slowed, crime grew. Nar Shadaa became a home for all forms of criminals, from slavers to smugglers. This rampant crime gave Nar Shadaa the nickname "The Smuggler's Moon." Think of this moon as a giant Mos Eisley, as Obi Wan said "a hive of scum and villainy." Its current state is much like it was in Kotor II, a bunch of slums with crime lords every 3 feet. If it enters the game I could see this being a major gathering point for trade and spamming.