We went in the first week of April. I cannot imagine the chaos in summer. The lines to get into the church, the bell tower were crazy. The bell tower lets people in every half hour, so it's a long wait, and this ticket doesn't help. In fact, the door employee was bouncing half the people away, rudely. He gave us a horrible time with our 3 day ticket that we had a screenshot picture of, so print paper tickets. We ended up not doing two of the five things because even in 3 days it was impossible to stand around if you had appointments at the other attractions (which are better by far) Go to the Uffizi, to see David, to the Medici chapels, to the Palaces, etc.

The tour description says tickets will be sent by 9pm the night before. They were not. I had to contact the tour operator and ask for my ticket. Ticket eventually arrived, but I got nervous wondering if the ticket would be sent. The climb up to the top is not for those who are claustrophobic or afraid of heights. Many tight passages, and we were forced to stop completely 2/3 of the way up and stay in a very narrow passage for about 30 minutes with no explanation. Part of the climb involves walking on a ledge high up within the dome. There’s plexiglass there for safety, but still it’s unnerving for those afraid of heights. If it’s raining, rain will spill into the stone passages and make steps very slippery in addition to getting you very wet. Also, in some parts you have to go down the same way as people coming up. Passing in tight quarters and in spiraling staircases is difficult.

If what you're looking for is a well organized exchange of tickets to climb the Duomo, look no further. Does not include an onsite guide which, for our taste and experience, is not really necessary. Had a little difficulty finding the tickets on Whatsapp at first, great communication from the seller. Very polite and responsive. We especially appreciated the helpful pictures of exactly where to go. For our family, the perfect Duomo experience. Thanks!