Oblivion - one of the most disappointing games ever. So much potential with free roaming worlds, character creation, skill/spell creation, unique armor graphics, epic world. Just boring though, most of the characters you can create are just ugly, tedious questing, enemy leveling was a horrid idea, repetitive world, dungeons all looked the same, and hated the controls.
Super Paper Mario - was just...eh.
Metroid Prime 3 - got bored after 2nd-3rd boss.
Warioware Smooth Moves - waste of money after the 1st couple hours.
Total War series - great in principle, horrible in execution.
Warcraft 3 - maybe I just sucked online?
GTA series - just bad