Like with the Natural Ergonomic Keyboard 4000, Microsoft tried to improve comfort and reduce strain without reinventing the device. Any departure that is too far from the norm tends to be dismissed by consumers, which is why ergonomic mice have had so much trouble catching on, but the 6000 is more of a tweak to the classic mouse than it is a reinvention. What it does is rotate your hand so that the thumb and index finger are lifted off of the desktop. This means your hand is slightly tilted and stress is relieved on the carpal tunnel and wrist. The overall effect should be improved comfort and decreased chance of a repetitive stress injury.