I never really got into the corrosive weapons, but that gun is pretty much the Borderlands equivalent of my favourite character build in Diablo 2. 20 points in each poison spell, corpse explosion, and decrepify, and put the bonus points that you get into bone shield. Basically, run into a group of enemies, decrepify them, poison nova a couple times, stab the biggest one, then run away. When the big one dies, blow it up to kill the rest.
I'm still using my shotgun that deals 145x11 damage with a 2.7 fire rate. It only holds two bullets, but "quick hands" fixes that problem.
It crits as high as 45k at point-blank.