The flight to San Juan from Atlanta was fine. We took a cab to the cruise ship, which is only $20, compared to the much higher rate the cruise line offers for transfer. The ride is about 20 min.
Embarcation was easy, and the staff nice. The 4 of us (2 adults and 2 boys aged 5 and 9) stayed in one ocean view cabin on the 2nd floor. The cabin was small, and the boys slept in two beds that pulled down from the sides of the cabin.
Compared to Carnival, I would say that the Summit is more upscale, there were very few children on board, the buffet food is excellent, the main dining food is very haute cuisine. The children's menu is okay, but mine preferred the buffet dining.
The children's program is comparable, but sometimes, there was a charge for keeping the children there over lunch or dinner, which I thought was a little much.
The islands were somewhat disappointing. A lot of tourist traps, boring souvenirs, and expensive.
We pretty much picked our own itinerary, and hired local drivers just for a trip to the beach or for the entire day, which is much cheaper than booking one of the shore excursions, which are very overpriced.
We had a very nice driver for the day in Barbados, Anthony (email@example.com), who took us around the island all day long for $80 and who was very knowledgeable.
The drinks on board were ridiculously expensive. The entertainment was okay, but nothing to write home about.
The staff was actually a little less friendly than the staff on the two Carnival cruises we have been on. It felt as though some of them were gritting their teeth to be nice and we had several problems with Guest Services and our credit card.
The debaraction process was better than at Carnival, less stressful and very organized.
In conclusion, I did not see much of a difference to Carnival, even though Celebrity is considered to be more upscale. I think I will go back to Carnival if given the choice.