Just completed a 12 day cruise to Northern Europe with Celebrity Constellation. The scenery was interesting and found the restaurant and cabin service staff to be attentive. The food was good in the main restaurant but left a lot to be desired in the cafeteria which I used for breakfasts only. The cabin was adequate but public areas often crowded, it being difficult to get a seat especially on sea days.
I and other passengers did run into problems with celebrity's new and very aggressive search and seizure policy when boarding the ship that I think potential passengers should be aware of. In rather gruff fashion you will be required to empty all your pockets and place all carry-ons, packages, jackets, etc through an X-ray machine. Then you will be required to step through a metal detector. If any consumable items are detected or metallic items they decide they don't like for any reason all these items will be confiscated.
I personally had a decorative tin of cookies, sealed specialty jam and honey, tweezers and nail clipper all confiscated. I requested the gifts I had bought be held for me but celebrity refused stating they will all be discarded. When I brought this issue to the ships customer relations department no explanation was ever offered other than to say that all consumables of whatever kind will be confiscated and discarded. However, other passengers I observed had none consumable gifts eg. sealed, decorative table candles purchased as a gift also confiscated.
I do not know what other cruise line policies are but if you plan on purchasing gifts at your ports of call I would advise getting their policy straight, in writing before booking. Overall, I thought this was an adequate cruise mostly because of the scenery but celebrity going overboard on the screening issue makes me think twice about future cruises, especially with celebrity.