Funny because I actually played the game, actually bought the controller, and it actually entirely solved the control issues. Further, I have used that controller for other games on the PC like Mirror's Edge, Prince of Persia, Geometry Wars, and Everyday Shooter.
The control issues have nothing to do with Legacy's failure and those control issues were easily solvable by a 20 dollar 360 controller.
Is Legacy a poor console port? Sure, despite the fact that MadDoc consistently claimed that the 360 and PC version were developed in parallel. However, control issues were an exceedingly minor problem within the game compared to:
1. the crappy multiplayer system with no game lobby with no chat, no support for services like GameSpy Arcade or XFire, and no leaderboards.
2. the very narrow set of supported video cards
3. the crappy graphics engine with horrific shadowing
3. the no official support for Windows Vista under which multiplayer did not function at all
4. the repetitive simplistic gameplay
5. the lack of any kind of dynamic single player campaign
6. the truncated and incomplete story-based single player campaign
Is that enough for you? And you will note half of those issues are endemic to the game itself whether on PC or the 360 and the other half are PC exclusive problems. So you had a crappy game that was made worse by being poorly ported to and practically unsupported on the PC. Control issues are exceedingly minor considering this list of problems.