Yup. I can attest to the value of doing sprints. I love them and they're excellent a building leg strength. Just look at 100/200m runners legs. Have to psyche my self up before I go to the gym to do them though (we have a couple of running machines that go up to stupidly-high kph and people that don't know what you're doing often look at you like you're insane), but I'm usually high off the endorphins for hours after
And like Naxis said, it spares muscle and burns fat like nothing else.