We just came back Disney Fantasy and did this excursion. I too was hesitant as I could not find many reviews on it when I booked it. That being said, it was one of the highlights of the trip. Mario, our guide, met us at the peir at cozumel and there were only 4 of us doing the excursion. They arranged for a taxi to take us to Playa Uvas ( he followed behind us) which is a small beach type club with a bar, small restarurant, beach front and chiars, etc. They have outside showers, bathroom and equipment there. All staff at the beach club were very friendly and acommodating.
The weather intially was rainy and he had us wait before attempting to snorkel due to the weather. I appreciated his looking out for our safety. When it cleared (and he went out in the water to test it out first) we started the excursion. Mario took us snorkeling ( even gave me a boogie board to assist me as I am not a good snorkeler), and explained everything, watched out for us, and snorkeled with us- diving down and showing us sea life and taking pictures for us. Always cheking on us which was nice. We then took a break and then went kayaking, which he again stayed with us, showed us what to look at and assisted us if needed.
Once back they served us fresh fruit platters and gave a coupon for a free drink ( I had a maguerita). I did purchase some souveneirs there as they had a small stand and the person there was very nice- not pushy. You could purchase food, but we didnt. He then asked us when we wanted to go back and he arranged a taxi back to the ship port. Would definitely recommend this excursion and am surprised more people at Disney dont do it. It is a bit of a workout,. but you could opt out of part of it if you wanted and stay at the beach. You are always wihtin eyesight of the beach. The entrnace to the water is a little rocky but they have sandbags for you to stand on to enter, and once you arein the water is a beautiful blue and warm. Play Uvas is less than 10 minute ride from the ship. Hope this helps.