The wife and I selected Celebrity for our latest cruise. This proved to be a mistake. We met the Millennium in Sydney, AU at great expense, for a 14 night cruise. Our deluxe ocean view cabin turned out to be about 20 feet from the forward crew quarters, and the room and access corridor reeked of dense cigarette smoke. Also, power outlets in the room didn't work and the couch was stained and cigarette burned. To their credit, Customer Service relocated us to a decent stateroom, but not before my wife developed a severe sinus aggravation due to the smoke in the original cabin. That, coupled with less than acceptable food (so cold it would never pass health standards in the States), resulted in her checking in with the Medical Department - which in turn resulted in both of us being put in isolation. For her 48 and my 24 hours (just for being in the same stateroom with her)of isolation, we received a $258 future cruise credit, which is 82% of what we paid for that portion of the cruise. I contacted them to understand how they felt this was fair, but they responded that they feel this is a fair settlement.
A recommendation - make sure you are really, really sick before you notify on-board Medical. Better yet, carry plenty of Imodium. As for us, we've made our last trip on Celebrity.