"The ML-3 offers remote control for two separate channels via an infrared LED beam, enabling automatic camera operation from a distance of up to about 26 ft. Auto triggering, delayed shutter release, single and continuous shooting are possible." The "Auto triggering" is the ability to release the camera's shutter when an object moves between the remote and the sensor connected to the camera, most useful for wildlife photography.
I got one in just over a week, great little gadget, only drawback I see is that it has no clip to connect to the hotshoe and or the camera strap. Not a big deal as most times it's going to be on a tripod anyway.
It really works well though and I highly recommend it, makes you wonder why the Nikon one is so expensive.