How hard would it be to screw up how a drum pedal works? There is a switch at the base of the pedal and a spring resistance to add some weight. As you push down on the pedal, the switch activates and registers as an input. It is an incredibly simple idea and pulled off just as well. I read some reports online of people complaining that it doesn't work. There is a little yellow piece (as well as plenty of instructions) that tell you to remove the plastic piece before playing in order for the pedal to function properly.
One of the different features the Metal Pedal has is that it's universal. There is a switch on the cable to select between Guitar Hero and Rock Band (sorry Rock Revolution players) and the cable is neatly coiled and stays out of the way.
I tried the pedal for both games and I put it through a stress test on Guitar Hero: Metallica on Expert +. Although I nearly had a heart attack playing some of those songs, the Metal Pedal worked fine, if not better than the standard one. The actual pedal is a bit wider than the regular one, so the frantic stomping will be sure to connect.
Some of the nice fringe benefits are the cool package art and style. The foot pedal has a skeleton lying on the face and studs adorn the bottom. The "metal" isn't just about what songs you should play, it's style and attitude are "metal" too. The other is that it comes with a splitter jack for double bass players. It is a small jack that stays discrete and functional.