The Metal Zone is an amazing guitar pedal for metal or other genres of music which call for extreme amounts of distortion. Other types of music would best be suited with a different pedal, as the Metal Zone doesn't sound quite right when the gain isn't turned up to a very high level, and the mid-range is a little weak. However, for thrash metal, death metal, black metal, or grindcore, this is what you are looking for. Do you find that you're speed-picking your notes, but no matter what you do or how softly or accurately you run your pick over the string, it just doesn't sound right? Get one of these pedals, turn the distortion and treble up, and Metal Zone will give you the tone necessary to let loose a sizzling fury of musical annihilation.
You can get highs that sound like a piercing air-raid siren, and a held power chord will turn into a sustained river of distortion. A good way to add even more power to your tone is to set the mid frequency a bit below where the treble is, and turn up the mids about half-way. The parametric EQ gives a wide range of timbral possibilities, and with a fair bit of experimentation you can find approximations of the guitar sound used by extreme metal bands as diverse as Slayer, Morbid Angel, Darkthrone, and Suffocation. This device is especially good for imitating the "Swedish guitar sound" used by early Swedish death metal bands like At the Gates, Dismember, and Entombed. Also, by turning the knobs down a little, the Metal Zone can be used for more mainstream varieties of music like nu-metal or grunge.
One may find that after using this pedal, that anything else sounds "weak". Indeed, when your ears are accustomed to the sound of a Metal Zone, you may return to using your previous method of guitar distortion and find it absolutely unexciting. Although other people, especially non-metalheads, may find your guitar tone intolerably extreme, to you, it is unimaginable to have it any other way.
It should also be noted that this thing is built like it's meant to be used by violent, abusive metalheads: it's extremely sturdy. Many guitar pedals are flimsy, and would break under the force of some furious musician leaping as high as he can into the air at the end of a clean part, his boots careening down on the device at the exact moment the drummer starts his double-bass pounding, but not this one. Indeed, even if one were to do something a little ridiculous, like jump down from the top of an amplifier onto the device, I'm sure this well-armored pedal could take it. This thing eats batteries for breakfast, lunch, and dinner though, so you might want to plug it into a wall if at all possible.
Overall, this is a good guitar pedal for what it is meant for.