It's really an audio interface designed primarily for camcorders. It provides xlr and 1/8" mini inputs for mic or line level inputs. Most consumer camera's don't have inputs other that 1/8" mini so can't accept mic inputs, nor can they usually accept line level inputs such as from a mixer.
I use these on my Panasonic camera's and they work great. The real nice part is that you can adjust the level during recording. On my cameras the audio level adjustment is buried in a menu, and there is no way to adjust it once you start recording...you have to stop, go into the menu to change it, and start again (not very nice...) With this interface, you can just turn the knob a bit if need be on the fly!