He is the main 'Villain' from most of the Borderlands series. I personally consider him to be a tragic hero after all it took: a bunch of betrayals, a terrible childhood, an almost genocidal event (the moon almost exploding via laser), two eldritch god like beings being awakened (The Destroyer and The Sentinel), horrible influences manipulating him, living in a corporate slog, being unappreciated for all his work, being seen as a laughing stock by his boss, a paramilitary invasion, impossible quests, corporate takeovers, and death of love ones, and a god relic being smashed into his face which drove him insane, to turn him in to the monster Pandora came to hate (or worship).
I ain't saying that trying to kill all the bandits and therefore most of Pandora is ethical, nor is the experiments he conducted with slag, I am just saying it is sad to see how he had fallen and the man that Handsome Jack was before didn't deserve to become that.