We use these to pick up the ambient stage sounds during theatre productions and non-miked chorus vocals. They pick up speech well, sometimes too well when people are chatting in the wings.
Pros - Small and easy to mount using the "keyhole" screw mounts on the back, built-in rubber insulation helps stop vibration. Cons - seem to work better when mounted vertically so we made some custom brackets to fix at the front of the stage.
With three of these across the front of the stage, we capture a good deal of dialogue.