We sailed on the Millennium from Singapore to Hong Kong and loved the itinerary, but the ship is old and tired. Having sailed on the Equinox twice, I love Celebrity, but wont be sailing on their older ships again. Cliff, our room steward, and Tiffani, our dance teacher were wonderful, but the rest of the staff just didn't match up to the service we received on the Equinox.
The internet was just awful, it was down more than it was working. The one excursion I took through the ship (Singapore at Night) was the worst tour I ever took, it was that boring and disorganized. Celebrity also continues to nickle and dime, like the scrapbooking class that was free and had a great teacher to show us how to do page layouts on the Equinox, now there's a charge and the teacher just handed out kits and said "have fun!"
I wish Celebrity would also upgrade their entertainment, and at least show movies on sea days if they cant provide more fun and interesting activities other than the same old tired art auctions and bingo. We liked the food in the dining room, but the buffet was your usual buffet food -- eatable but nothing special, and usually very crowded and disorganized. We loved Qsine, the food was different and interesting, it was well worth the extra money, but dont bother with the Olympic specialty restaurant, the service was slower than molasses and the food was nothing special.
Having said that, we met some amazing friends through the Cruise Critic boards and we thoroughly enjoyed our excursions off the ship, I would would go back to visit Singapore, Bangkok and Vietnam (Hong Kong was a little too crowded and hard to get around for my taste.) I would highly recommend overnights in Vietnam and Bangkok, you really cant go back and forth to these ports (especially Hanoi) and see very much in one day. Hotels and restaurants are very inexpensive in Vietnam, just watch out for the mopeds, they don't slow down for anyone, even if you have a green light!
Would I sail on Celebrity again? Definitely but only on the Equinox or one of its sister ships, definitely not on the Millennium.