Works great on EL34 valves such as Marshall amps, not so great with 6V6 valves as used in fender amps. Volume is a bit loud, but as the gain works very differently with different valve types it's worth a giving it a go.
I bought this pedal because i wanted to play Van Halen. This pedal has a good crunch sound. The only con is that you have to be easy on the controls, because it can be too loud very quick. The distortion is strong enough to combine with my flanger and i am very satisfied with the sounds i get out of this pedal, especially for 30 bucks!