The coupon, I believe, reads "up to 50% off". I know some hotels only offer 20-30% off with the card, while others will set aside rooms at various price levels for the card on a given night. For example a hotel may choose to set aside 1 room at 50% off, 5 rooms at 35% off, and 10 rooms at 20% off. Remember the percentage is off rack rate, not necessarilly of the best rate.
Jim