We did the Magic from Barcelona last year. There are significantly less young American children on our cruise when compared to a Caribbean cruise. People don't necessarily want to pay for transatlantic flights and an expensive cruise that their kids might not remember or appreciate. My cruise was about 80% over 14 years old. Disney also did a great job of providing Adult Only excursion options.
Also, the port excursions are long. We had a 10 hour excursion on our last day and got back with barely anytime to shower and change for dinner for the Main Dining seating. Because the excursions are so long, we barely spent anytime on the ship and were exhausted on our 1 day at sea. When it came time for the Livorno port, I was so happy that we had already been to Florence because it meant we could have a "light" excursion to Pisa which was only 4 hours because it meant we could relax on the ship a little.
All the excursions we did were amazing and I am so happy we did them. Most of our tour guides were friendly, knowledgeable and spoke clear English. We only had 1 who had perfect English vocabulary, but her speech pattern and accent were difficult to understand so we really had to concentrate.
This should also go without saying, but if the guide says to meet up at a certain time, you definitely need to be on time. We had a situation on Monte Carlo where 2 people held up a bus and because the buses can only pick up groups in a specific area in a very specific procedure, it had to wait for these two people. Unfortunately, that bus couldn't leave and prevented other buses from being able to load their passengers so hundreds of guests were crowded in a tunnel in Monte Carlo on the side of the road waiting for two very rude guests who didn't seem to think what they did was a problem.