Well for light bumps and thumps, the Icon isn't going to provide any more protection than any other neoprene case. I've actually found for light bumps it'd appear to be worse for protection because of the hard plastic inner-molding contacts the edges of the Mac. However, the ultimate selling feature of the Icon case is the Tensaerlite material, which is designed to absorb rapid, high-impact contact with surfaces, i.e. dropping the entire thing on the floor. The physics of the case protection are only activated with such a hard impact.
There's no downside to TOO much protection, my comments were merely geared to the fact that the case drastically increases the size of the laptop in a case.... whereas the options like the Crumpler Fug (medium protection) and Radtech Sleeves (little or no protection except from dust) provide a calculated balance of form factor elegance and protection level.
I wish Incase made the same model with the same magnetic closure without the Tensaerlite material. Would trim nearly 15% of the cases's size. Oh well. Anxiously awaiting my Crumpler The Fug to be delivered from Australia. Until then, the Icon will have to do.