Maybe the difference between our wonderful experience and the previous posters' negative experiences was that we began our cruise in Seward and cruised to Vancouver. From the embarkation through the entire cruise, we had nothing but a wonderful experience. There were 9 of us, including 3 children, and a grandmother who injured herself on the land portion and required a wheelchair. Celebrity was outstanding in every respect concerning both the wheelchair and the children. Indeed, I do not think that any company could have been kinder, more thoughtful, or more helpful. Celebrity did everything possible to ensure that my mother was able to enjoy herself despite her injury. And the children absolutely loved every moment. The staff, both in the kids' club and elsewhere on the ship, were so nice and friendly to the kids. Our cabin steward, Charlie, even brought the kids a special treat (chocolate covered apples) one day, just because. He was truly a gem.
We ate dinner every night in the Metropolitan, the main dining room, and breakfast there several mornings as well. The food was always good, and some times excellent. When we had something we did not care for (a smoked tomato soup), they quickly replaced it with something else. They took all sorts of special requests ("I'll have the spinach ravioli with cream sauce, but can I have it with tomato sauce and no spinach, but sauteed mushrooms instead?") with grace and never once told us no. We did the Select Dining, and rarely had the same servers, so this fabulous service went throughout the dining room. We have special kudos to Sasha, one of the Sommeliers, as well as Ana and the Australian Head Server. They were so considerate and helpful. The bartending staff was also extremely good; they worked well under pressure, and were accommodating.
The room was as expected -- small but efficient. It was tight with 4 people who had overpacked, but we had room for everything. My mother and sister were even able to fit the folded wheelchair in their cabin.
The shows were high quality, although I do not particularly like the "review" style shows that are prevalent on cruise lines. The performers were all very talented. We liked all of the Celebrity Life programs we attended, particularly the Captain's talk on navigation. It was fascinating.
If you asked me to think of any negative, the only thing I can think of is that the gym did not have a wide variety of free weights, particularly in the 2-15 lb. range, and the yoga mats all need to be replaced. I also did not think that the gym staff was attentive enough; they should have been monitoring the equipment more and asking if people needed assistance. I don't know if anyone did need assistance, but I believe that a high-end gym should have staff checking in with the guests.
In all, I cannot understand why anyone would have been disappointed with their experience on Millennium. Ours was wonderful.