This was only our 2nd Celebrity experience out of 20 cruises, the most being 7 on Princess. Overall, the differences between the 2 are negligible.. only individual experiences will differ.
When we booked, Aqua was only a few hundred dollars more than regular veranda, so we took advantage. With my spouse's food allergies, the Blu dining room seemed the logical choice...not so much.
The 1st night a note in room requested we come between 6 and 630 to dine. We had a hard travel day, so I went to the maitre d' and asked if we could come later. "No problem, Susspeople4, you can come anytime, we have open seating. Your allergies are in the system and we will attend to them." We arrived at 7p and were greeted with a 45 minute wait. There was no dairy-free margarine as requested. At the 3rd port, maitre d' personally shopped for it successfullly after 2 failures. Menu in general seemed no different than a main dining room.