We found this place on our own. We were disappointed with the rest of the port and tried this place for something to do. Very nice spot. Staff was friendly and they have a perfect safety rating dating back to the 80s. Trip was about 1.5hrs altogether and a lot of fun.
As mentioed about Grand Cayman was a bust in my opinion. Run down and hardly any shops open. Plus you have to take a small boat on to land. That resulted in more time waiting.
Cozumel was much better. It was cleaner and more organized and also the ship pulled right up to the pier. This made it much nicer because you could grab some loot at the port and then drop it back off to your room and go back for more ;).