First off we're frequent cruisers, but not "super cruisers". This was our 5th cruise, we've done 3 in the Caribbean (2 on Carnival, 1 on Royal Caribbean) and a cruise on Carnival in Alaska. Celebrity Reflection itself was the best of the 5 from an overall shipboard experience. Embarkation/debarkation was organized and easy, All the port access were wonderful. We were in Concierge class suites (traveling with my wife and mom in law - we had side by side suites which they opened the gate between the balconies so we could get access to each other's cabins and have an extended balcony). We ate at Murano (5 star fabulous), QSine (fun and interesting and OMG we were stuffed) and the Tuscan Grill (average steakhouse kind of fare). If we'd done it over we might have done Murano 2x instead of Murano and Tuscan. Our Concierge class suites came with a bottle of iced champagne on arrival, and full butler service. you get free in-room espresso and cappuccino, and a full menu for any meal in the room. butler server was amazingly attentive, right down to being able to ask (and have remembered) exactly where you wanted your blankets tucked in on the somewhat weird rounded end bed. We never asked for anything that was delivered late or that we had to wait for. Concierge class includes priority tender tickets - we only Tendered in Santorini and we were on the first boat to cast away. We were really spoiled by Concierge class and would love to do it again :)
The ports were all fine and fun - interesting. Except for Amalfi coast/Pompeii we did our own thing in the rest of the ports and had no problems. Our advice for Istanbul is A) figure out the tram system before you get there and where the tram stop is near the ship, but DO take the time to walk one way or the other over the bridge to the old town because that's a wonderful experience. Also B) Pace yourself. We were so tired after day one in Istanbul that we skipped day 2 (the morning only till noon) because our feet were so tired. Hire a private guide for Ephesus - we used Melitour and had Ahmet and were exceedingly pleased. Hire a guide right at the acropolis for Athens - we hired a guide just outside the main gate and for $100 Euro got a private 1.5 hour tour of the entire site. On Santorini we rented a car ($50 or so) and drove to Oia for the day - well worth it and easy though the car company took a bit to find us. Mykonos we just wandered on our own, The Amalfi coast you DO want to have someone else drive, and a bus tour's not a bad option - especially if you get the tour guide as part of the deal for Pompeii.
We flew AirTransat out of Toronto (we live about 3 hours from there) and everything was great with them.
My wife's mom is a vegetarian and that was no problem throughout the trip - everyone was very accommodating, airline, cruise ship, tours, etc.