I have one of those, too. Two issues: the knob fell off so it's now got an old knock off strat knob on it and the battery loses contact, so I have to push it in while using it. But, it's very handy, indeed.
I have one of the Behringer ones as well, it's very cool, except that the power switch keeps sliding to the on position and it runs the batteries down.
Still looking for the perfect one....