[1] First story, Come Then, Mortal -- We Will Seek Her Soul, has Nifft and his companion Haldar are hired to complete a lover's vengeance from beyond the grave, with a valuable magic item as their payment.
Second story, The Pearls of the Vampire Queen, involves Nifft and another companion, Barnar, poaching valuable swamp pearls, and interfering with a ritual by the titular vampire queen.
Third story, The Fishing of the Demon-Sea has Nifft and Barnar magically compelled to go into a demonic underworld to save a merchant prince's son, that has been caught by a sea-demon he summoned.
Fourth story, The Goddess in Glass, has Nifft at the mining city of Anvil's Pasture, involved in the efforts to save the city from a collapsing mountain with the help of a cult of a dead alien goddess.
[2] Dave Langford reviewed Nifft the Lean for White Dwarf #42, and stated that "In this garish hell, people suffer grotesque transformations and torments, described with vast relish and elaboration; the visceral variety of Shea's unpleasantness never flags, and the gaudy landscapes infect your dreams.