Very harsh ride, high rolling resistance, and added weight. Wouldn't consider them at all for a long commute since the higher rolling resistance would slow you down too much and they make the ride much less comfortable.

Had a friend who used them on a short commute (about a mile) figuring that they'd be worth it for not having to allow the extra time margin just in case of a flat tire. After about a year he started repeatedly breaking spokes and we think it's due to the harsher ride of the tires causing fatigue damage.