We are a married couple in our mid-30's and are not usually cruisers, but booked this mainly for the destinations. Overall the cruise went well, despite a minor bout of food sickness. Embarkation went very smoothly, although it was quite a walk to get from the train to the ship in Venice. Disembarkation went smoothly as well; we opted to carry our own luggage and pretty much walked right off the boat and then took a cab to our hotel. We had an ocean view cabin which was spacious and in great condition. Service was overall very good, and the entertainment was OK despite the fact that they really put in a lot of effort to try and put on a great show. Food was just OK - there was no significant difference between the dining room and buffet food, and we did experience minor food sickness during the cruise. It did pass in a day or so, and the overall cruise rating would have been higher if it wasn't for this incident.
Ports - booked excursions for half of the ports and mostly through the ship; the only one that we could find a better deal through a 3rd party was for the one in Istanbul.
-Venice - took the Alilaguna to our hotel near St Mark's/Doge Palace (~15 Eur/ea). Rialto, Santa Maria, and all other main sites are easily accessible by walking or Vaporetto water taxi. Venice is a little overwhelming at first due to language and the tiny streets, but it gets better after you get your bearings straight and realize how to catch the water taxis in the right direction.
-Athens - saw the Acropolis/Plaka by ourselves. Piraeus train station is not easy to get to from the port, depending on where the ship is docked. We gave up looking for the station and just took a cab (25 Eur), and returned by taking the train (0.7 Eur/ea) to Piraeus station and then walked a mile or so back to the port. People here were extremely friendly and helpful.
-Kusadasi --we took an excursion to Ephesus/St John's/Virgin Mary Shrine and were very impressed with all the sites. All the sites were pretty spread out so it was much easier through an excursion.
-Istanbul - took excursion to Blue Mosque/Hagia Sophia/Topkapi Palace. The Mosque and Hagia Sophia were awe-inspiring, and Topkapi was very crowded but had some incredible jewelry on display. Traffic was awful so this would have been difficult to do completely by ourselves.
-Mykonos - took an excursion for the town/beaches and the monastery at Ano Mera - just didn't want to deal with the logistics here and relax. Could have also just taken the shuttle into town and taken a short walk to see Little Venice/Windmills...
-Naples - took a bus (~7 Eur/ea) to Pompeii and returned to Naples with time to spare, so then we walked to Sanservo to see the Veiled Christ statue before heading back to the ship. Bus station was relatively close to the port - will have to ask the local Information for directions. We originally wanted to take a ferry to Capri but the line was ridiculous. Naples is not the nicest or cleanest City, so we walked pretty quickly the whole time...
-Florence - took excursion for Florence/David/Uffizi. Florence is not to be missed, with incredible views around every corner. Rome is really far away from port, so doing this on your own would be difficult.
-Rome - took an excursion for Coliseum/St Peter's/Vatican Museum. Again, not to be missed, and difficult/costly to coordinate on your own due to port distance from Rome.
-Monte Carlo - walked to the nearest bus stop and took line 2 (~2 Eur/ea) to the Exotic Gardens (excellent view of the city/coast), about 20 minutes away. Took the same bus back to the "Rock" (Monaco-ville) to see the changing of the guard, the cathedral, and aquarium. Could also have just taken the elevator right up to the "Rock" from the port and spent all of our time there. This is one of the nicest, cleanest places we have ever seen.
-Barcelona - checked into our hotel and found the nearest Metro station. The Metro is relatively clean, very efficient, and covers the whole city. We bought all-day passes for ~7 Eur/ea and headed to Sagrada Familia first to beat the lines - definitely add the admission for the elevator ride up to the "temple". Then we got off at the Urquinaona stop for Palau Musica (expensive to get in), and then headed to Jaume stop on the same line for the Gothic Quarter. Spent some time at the Catedral Barcelona (truly gothic) and in the Quarter, before walking to Las Ramblas and soaking in the scene. Took the Metro from Liceu station back to our hotel for some much-needed rest. There is just too much to cover in Barcelona for one day...