This was our second cruise on the Constellation, the last being in the Baltic in 2008. That experience was very good, this one was even better in many respects. Delightful and friendly staff, mostly good service, good to very good food. Ship was showing a bit of age, but was well-maintained. Given the enticing fares these days, a great value. The only real disappointment for us was the conduct of the excursions. I think the Constellation is new to this route, and it showed. Excursions were weak (their European excursions were pretty good)and not well organized. The land excursions during the canal crossing were bungled as the tendering process was not well planned, resulting in visits to tour stops as they closed or in the dark. Our best excursions were the ones we'd pre-planned ourselves (highly recommended, but do your research!) but that's not an option with Celebrity in Panama. A mild disappointment was the "Celebrity Life" classes, purportedly designed to teach lifestyle improvement. They are really selling questionable concepts and products. Stay away.
Recognizing not everyone is as excursion-oriented as we might be, I would not hesitate to recommend the Constellation for a satisfying and enjoyable cruise. While I would not necessarily commit to Celebrity for future cruises, they will certainly receive favorable consideration.