Oval chainrings work because a rider does not produce power evenly through a pedal stroke; they maximize the part of the stroke where power is produced and minimize resistance where it isn't. Oval rings make the spin cycle a lot smoother and are easier on legs while climbing. Believe it (or not), but a round chainring doesn't transfer torque to your rear wheel as smoothly as an Oval one. You will actually feel your stroke to be more "round" with an Oval shape than with a round chainring.
Why does it matter? Traction, Traction and Traction. With oval rings, rear tire traction improves greatly on loose and slippery terrain. Your legs will be less tired and your speed improved. Climbing will become easier then ever before. It is the world's best oval chainring.