We used Discovery Mundo to take us from Cancun airport to the ferry dock both ways. We arrived a little late in Cancun but there were there, no problem. When they came to pick us up at the ferry the next week, the drive was about 15 minutes early and actually came and found us where we were sitting at the bar/snack bar.

Both our drivers were nice and they drove very well. Oh! I almost forgot to mention the pricing -- totally worth it. In fact, for the service, I think they could get away with charging more! I would recommend them, no question.