Initially I was dubious about the use of this pedal in our band's full lineup since we already have a backing singer. However, instead I found this pedal to be of great use.
The main reason I purchased this was for the dynamic compression and EQ included in the tone options. A much cheaper alternative existed within the TC-Helicon range (for £85), but I felt that having harmonies may be useful in my solo work.
The compression and EQ work very well; subtly (but noticeable) improving the tone of my amplified voice. For most of our set I now leave the tone features switched on.
The doubling feature works very well to boost the thickness of the vocals.
The harmony features (the main reason you would buy this unit) can be a bit tricky to sound natural at times. But with a bit of adjustment, picking the right harmonies for the song and adjusting the level, I have found this to add some great textures and colour to songs.
As mentioned, we already have a backing singer, but by producing harmonies separately. It allows us to use the vocals as an additional instrument whilst layering lyrics on top.
All in all, a very good buy.