I like playing Steve Vai stuff on guitar and wanted this instead of a Morley, because of its greater treble and its auto on/off (just move the pedal to activate it). Its true bypass, so no noise when off and gives a wide range wah.
Amp on Clean = terrific wah, really nice funk, blues expressive.
Amp on Clean + overdrive pedal = terrific wah, really nice funk, blues expressive, but a little hiss
Amp on Dirty + overdrive pedal = good wah, can get muddy, but still clear enough to achieve full depth wah scoops, with some hiss
I mention hiss, but that's just at high gain, and not noticed when playing in a band volume.