The queue at the door is absolutely tormenting, especially under the sun. Don't take care of the people rushing out of the line to buy tickets. You can buy tickets online if you want to avoid queuing. There are too many people in the Sistine courtyard, especially overcrowded. Most of the cases can only be seen roughly with the flow of people. It's better to travel off-season, otherwise I'm too sorry for the 16 Euros ticket.