We booked through Negril One Stop in late 2009, it was a good deal and smooth transaction. Hotel reservations were exactly as stated.
I did not have luck when trying to use the one stop card. Along with the discount card, you are given a sheet of paper with the discounts for various businesses. I tried to rent a motor scooter at two different establishments for the rate printed on the discount sheet. At both places I was told that it was not possible to rent a scooter anywhere in Negril for the price shown on the discount sheet. I didn't follow up on this with Negril one stop, and I did not bother with the discount card after the initial failure of the card's acceptance at two different places. Hopefully other folks have had better luck using the card.
By the way, the deal was $20/day for a scooter rental, (still low season in the first week of December). I've been able to get a price of $25/day at different places, but have never been able to negotiate a scooter for $20/day.