We had never cruised Celebrity before, only Princess so we didn't know what to expect. The Constellation did not disappoint us. It is a different experience from Princess. There is no "Wow" factor when you enter the Constellation - the main lobby is nicely appointed but not palatial. The main dining rooms are lovely but not magnificent and the various bars and lounges are nice but not spectacular. The art throughout the ship is very modern and not to our taste. The staff are great though. They seem to be younger than Princess staff and just as helpful.
The ship had just gone through a Norovirus outbreak (previous cruise) and the staff handled the situation well. Our room was great - it seemed larger than our previous rooms on Princess and had an ocean view which we enjoyed. The shower was quite large and great pressure and very hot water, all pluses, although we were on deck 2 and someone from deck 9 complained about the pressure. The downside is the hangers which are the ones that are "attached" to the bar in the closet - not classy and a real pain. Another negative is that the fridge was fully stocked with minibar items which we had to ask to be removed so we could put water in there.
The ship's tours were excellent, although a definite negative is that you have to pay upfront and they are non-refundable or transferable the day before the tour (we couldn't change our mind and do another tour without paying for both, even if there was availability (very unlike Princess). Entertainment - the shows exceeded our expectations. The cast had multiple stars and seemed to be a better calibre than our previous cruise experience with Princess. The other entertainers were lost in the shuffle and their shows were poorly attended and although some of them were good, others were just plain awful. We liked the fact that Celebrity does not spend all day announcing the activities that are ongoing on the ship. Dining Experience - we chose Select Dining and thoroughly enjoyed the experience! We had the same table and same staff for the entire 12 days for dinner and they were superb, thanks to the very obliging Maitre D'. Celebrity has a separate Sommelier, who is extremely knowledgeable and that is also a definite positive. The food in the dining room was top notch and a great selection. It wouldn't matter what your tastes are, they had something for everyone. We also really liked the buffet at lunch (more so than the dining room, which is only open on sea days). The highlight for us was the Asian Station, which is apparently a staple on all the Celebrity ships. We did not go to the Speciality Restaurants, although we had previously booked before our actual cruise (based on the on-line menu). When we went to look at the restaurant (Ocean Liners), the menu posted outside the door and the menu posted on Celebrity website were different. In speaking with the Restaurant Manager, he informed me that they had changed their menu over 3 months ago. This is also a huge negative for Celebrity - their website is awful ,hard to navigate and out-dated. We called customer service once before we left and no one ever telephoned us back. The only other drawback to the dining experience was some of the staff trying to "upsell" on the Speciality Dining at lunch time in the buffet area. They would come to certain tables and try and promote you to book a night in one of the Speciality restaurants. It was definitely not classy.
All in all, we loved our Celebrity experience and would definitely cruise with them again in the future.