That right joystick, "c-stick", was an abomination.
The cutout was an octagon - okay fine, makes sense, as many games use 8-directional joystick input. But they put the flat sides in the directions people press - pressing up, you hit a flat surface. How does that make any sense? Unless you hit it perfectly normal (physics/force "normal"), there will be some component of the force acting to move the stick to a side. It's a subtle flaw but absolutely inexcusable, like they went out of their way and brainstormed for hours about how to fuck up a simple joystick.
Durability was also a huge issue. I don't know of any well-used controller that didn't develop issues within the lifetime of the system. You can really feel the difference between a new & old GC controller, because the new ones actually work, the joysticks aren't flopping around loosely and failing to register some directions.
Lucky for Nintendo's quality control reputation, they came out with the wireless Wavebird midway through and everybody needed one. Quality was a little better on the joysticks and it helped most owners spread their play across multiple controllers extending the perceived longevity of the controllers.
What a piece of shit. This fucking guy, "it was the best controller period." Get the fuck out of here.