This service is amazing, was punctual, efficient and cheap!. What you pay for this is the same that you will pay for a collective service. I used it, I was expecting a small car since only my wife and I were the passengers and they used a nice big van (same that is used for collective service), very well air-conditioned. Driver was so helpful and did the best I like: not talking. He didn’t ask for anything, he didn´t mention anything, was a peaceful trip. Best of this service is that they charge you for trip not for person so if you are traveling with your family is a nice solution, even for two I think was cheap so for 3 or 4 will be cheaper.
You can schedule your trip on internet and pay in advanced so when you arrive you don't need to worry. But if you which you can also pay cash when you arrive so they have both options for you.