From 1d4chan

Basically Rogue-like Psionic class, except we already had the Psychic Rogue which is mostly superior to the Lurk with better power access and Backstab dice progression. The Lurk gets a lot more flexibility thanks to its wide access to augments, allowing it to apply crits and backstab damage to undead and constructs, or apply backstab damage without needing to set it up. This is resource intensive and means burning Power Points as well as it lacking good backstab dice without burning pp and multiclassing or taking prestige levels in Assassin. Where as the psionic rogue gets better Backstab dice progression and doesn't need to burn so much PP to bring the pain.

The big reason nobody gives a damn about the Lurk however is that Lurk originated in Complete Psionic, an awful book Psionics fans hate for being designed by people who seemed not to understand the psionics system. Psychic Rogue on the other hand was part of the web series The Mind's Eye which was not only legitimately and completely free, but well loved for supporting a system Wizards of the Coast rarely bothered to support in the books proper.

Dungeons & Dragons 3rd Edition Classes
Player's Handbook: Barbarian - Bard - Cleric - Druid - Fighter - Monk
Paladin - Ranger - Rogue - Sorcerer - Wizard
Player's Handbook II: Beguiler - Dragon Shaman - Duskblade - Knight
Complete Adventurer: Exemplar - Ninja - Scout - Spellthief
Complete Arcane: Warlock - Warmage - Wu jen
Complete Divine: Favored Soul - Shugenja - Spirit Shaman
Complete Psionic: Ardent - Divine Mind - Erudite - Lurk
Complete Warrior: Hexblade - Samurai - Swashbuckler
Dragon Compendium: Battle Dancer - Death Master - Jester
Mounteback - Savant - Sha'ir - Urban Druid
Dragon Magazine: Sha'ir - Deathwalker - Fleshcrafter - Soul Reaper
Dragon Magic: Dragonfire Adept
Dungeonscape: Factotum
Eberron Campaign Setting: Artificer
Heroes of Horror: Archivist - Dread Necromancer
Magic of Incarnum: Incarnate - Soulborn - Totemist
Miniatures Handbook: Favored Soul - Healer - Marshal - Warmage
Ghostwalk: Eidolon (Eidoloncer)
Oriental Adventures: Samurai - Shaman - Shugenja - Sohei - Wu jen
Psionics Handbook: Psion - Psychic Warrior - Soulknife - Wilder
Tome of Battle: Crusader - Swordsage - Warblade
Tome of Magic: Binder - Shadowcaster - Truenamer
War of the Lance: Master
NPC Classes: Adept - Aristocrat - Commoner - Expert - Magewright - Warrior
Second Party: Mariner - Mystic - Noble - Prophet
Class-related things: Favored Class - Gestalt character - Multiclassing
Prestige Class - Variant Classes - Epic Levels - Racial Paragon Classes