On street vehicles it's good. Limited slip allows much better forward movement when the road is slick. When a car is turning, the wheels on the outside of the turn travel a longer distance than the inner ones, so axles have a set of gears that allow one wheel to turn faster than the other while allowing both to continue to receive power (the differential gears). The problem arises when one wheel has less traction than the other. The differential allows power to continue going to the "loose" wheel causing it to turn a lot faster than the one with traction. This is why a car in the snow will sometimes spin one wheel while the other (which still has traction) stops. Limited slip detects the out of control wheel and locks the differential, causing power to transfer back to the one with traction, which can move the car. As soon as the wheels get closer to the same speed the locking action relaxes so the differential can again allow the wheels to turn at different speeds.