Pros:
If careful, with ambient pedals, can produce heavenly sounds. I produced some unrepeatable demos and tracks with it. It sounds like more than an instrument, a keyboard or synth, because of the integration with the guitar.
Can blend the guitar and synth sound.
Has two outs
Cons:
Often the upper mids, high notes on the guitar are not registered well by the pedal, as if you turned down the volume almost all the way
The sounds are often overpronounced and toyish, the pedal is very, very sensitive