On our recent map updating trip we stopped by Cancun's new terminal to check it out for you, obviously since we weren't flying out of terminal 4, we could only get into the departure area, not the gates or arrivals.
If you are arriving at the Cancun Airport and want to get to your vacation in the most efficient way possible, a private car service from the Cancun Airport is the best way to go. There is no waiting and your bilingual driver is there ready for you to arrive.
If you are thinking about taking the ADO bus to Cancun Airport from Playa Del Carmen but no sure how, here if your simple guide (and how to get from the airport as well). Note: Many "official" looking people will offer help when you exit the terminal.