I use this product with an acoustic guitar by attaching it to an edge of the soundhole. For that purpose the gooseneck of the pickup should be a bit longer to get the positioning over the string right, but it works decently well.
The sound is surprisingly good for the money. For downsides, I have to note that despite the packaging states that this set should contain a small mini-xlr to xlr adapter, this set only contains the belt pack with battery compartment. The belt pack is quite bulky and unneccessary with phantom power from the PA system, so a small mini-xlr to xlr adapter would be considerably better in this situation.