There is not a single piece of starwars literature where you truly get to know the guy. Frankly at the end of the day hes a cautionary tale for both sith and jedi.
Except for, y'know, Tales of the Jedi: The Golden Age of the Sith
and Tales of the Jedi: The Fall of the Sith Empire
, wherein Naga Sadow is a major figure in both story arcs.