Link's Crossbow Training springs to mind first. Expectations were null and void, however just that the lofty adventure franchise took a detour into the shooter genre is an embarassing prospect. The game itself is average at best, serving as little more than an abbreviated Twilight Princess extension for twitchy fingers as well as a means of raking in money for the semi-flop Zapper peripheral via its titular character.
Indiana Jones and the Staff of Kings might deserve a passing mention. Its shiny new Euphoria environment-physics engine was hyped up to be something groundbreaking, especially so for Wii. The final product turned out at best average with somewhat wonky controls and a gameplay scheme that tried to accomplish too much.
Outside of Lego Creator and Lego Racers, the Lego games kinda disappointed me. Sure, the first few Lego Star Wars games were simple, enjoyable romps. But the brand proceeded to acquire all these IP licenses, carting out the same "smash-stuff-and-collect-studs" gameplay for various popular franchises. I wish their games would stay loyal to building and creativity. (There was Lego City last year, not sure how that worked out.)