I mainly use it with my Takamine jumbo acoustic electric for worship songs. I find it especially useful when I have another acoustic guitarist next to me. It gives your chords some different voicings and adds a little bit of "freshness" even to some old songs.
Pros:
- easy to use
- high quallity product, feels sturdy and solid
- "first aid" for situations when you don't have an arrangement for two guitars, and you don't want to sound boring with two guitars playing the same thing
- encourages creativity
- excellent for fingerstyle players
Cons:
- takes some time to get used to new chord shapes (if that can be a true con...)