My family and I just did this excursion on the 6/25 cruise. I was going to post a complete report once I get laundry done and have a chance to put everything together, but here is quick report on the horseback ride.
We booked the midday tour. We met at 10am in Diversions and took the tender as a group to the pier. At the pier we were met by our tour guide and escorted to the bus for a 15-20 minute ride to a nice hotel on the beach. Once there, they took our drink orders for after the ride. Choices were water, Coke, or beer. We walked down to the beach to mount the horses. The horses seemed well cared for, just stubborn as most rental horses can be. We rode from there down to the end of the beach where the guides took our photos with the Magic in the background, and then rode back. The wranglers will assist you in getting your horse to trot if you like, but you can not take them down to the water. The ride takes about 1 hour. After the ride you pick up your drink and are free to enjoy the hotel for about 30 minutes before the bus ride back to the pier. There is just enough time for a quick dip in the hotel pool or the ocean. They do make a stop downtown if you want to shop before returning to the ship, but if you get off you are on your own to get back to the ship. It was HOT on the beach and if I had it to do again I would book the early morning tour. There is so much to do that you could easily stay in the area for several hours. There are parasailing, waverunners, sightseeing, scuba and snorkeling tours that you can pick up. There is not enough time to do it all, unless you choose to stay and take a taxi back on your own. The kids and I chose to return with the bus and were at the pier by 1:30, dh found a scuba tour and went his own way.
Over all, we had fun, though I do wish there was more beach time programed in. A few words of advice, wear long pants, use sunscreen, and travel light, there is no secure place to leave items. We brought towels and they were left on the beach with one of the guides while we rode.