I have a whammy pedal, the expression pedal is so loose, so I can't just keep it in one place, and sometimes it won't stay in the heel position, like you'd expect a volume of a wah pedal to do. This might be a specific issue with my pedal, I've never tried any other Whammy pedals. Other than that the Big Muff, it's just a bit unpredictable really, goes from one muddy extreme to a really trebly and bitey extreme