Whilst similar to the Grigri the Eddy is less prone to accidental misuse (it's still not infallible!) and is a very neat and easy to use device a great new innovation.

Eddy is the perfect belaying device for sport climbing for either novice or the experienced climber. The Eddy doesn't need much explanation and in simplicity is safety. Easy to thread, the rope follows logically the rope flow. A controlled descent with an emergency break system eliminates the "panic pull" syndrome which can lead to serious accidents. The Eddy provides maximum safety whether top roping or lead climbing with easy paying out of rope to the leader. Can be used for single ropes with diameters from 9 to 11 mm.

Relevant Link
PDF: User Guide