Hard to use, and my god - the switch.
I can only confirm what others said: it takes a bit of practice. You might find yourself onstage silently sliding the thing around looking like a dang fool otherwise.
But I really can't get over how cheap and flimsy the on/off switch is. That is a scandal.
By the way, acoustic dude take note: The thing appears to work to some extent on any steel-stringed guitar, with or without pickup.
Biggs on 2013/06/25