It's really all about what kind of traveler you are and what your expectations are for a good trip.
In May we took a 7 night Western Med Cruise (our third with Princess) from Istanbul to Rome. Our ports of call were Mykonos, Valletta, Messina and Salerno.
Embarkation: was a bit of a bummer. We got an email the day before saying that due to a lot of cruise ships in port and Turkey's lengthy immigration clearance procedures, they needed to stagger passengers and asked us not to come until 4PM. When we got there, we were the only passengers there! The terminal was empty except for us and the ship's reps! Pretty annoying to get on the ship that late and go straight to muster.
A great, vibrant city. We had a private guide take us to the Hagia Sophia and on a tour of the Cisterns, followed by Topkapi Palace. This was our second visit to Istanbul and we want to go back again!
We tendered in Mykonos and rented quads and drove along the coast to Onos Beach, where we lunched and sunbathed. Heaven! Afterwards, we walked through town and had sundowners in Little Venice. A wonderful day