Has Celebrity slipped? Some people writing here think so. We've sailed many times with Celebrity in the last 10 years, the latest in June 2013 around the British Isles. My view is that, on Infinity at least, Celebrity is still a well-run operation, and if it has slipped at all, it is down from excellent to very good. My wife is a stickler for cleanliness, e.g., and the ship certainly passed muster with her.
My main complaint is that, like many cruise lines, I believe, Celebrity has introduced more classes aboard ship, the better to squeeze more money from hapless passengers. We were talked into booking on Aqua class, e.g., which, for considerably more money offered us a cabin with such things as thicker towels and a bigger shower head. Gimme a break. Not worth it. Those traveling in ordinary indoor or outdoor cabins are disadvantaged by these additional classes above them, because these classes are, I believe, given priority on embarkation and disembarkation, thus inconveniencing others. It's a gimmick, not worth it, and just bothersome to us "classless" Americans.
This is subjective, but my wife and I felt the breakfast buffet was not up to what we experienced on Celebrity years ago. But it's marginal.
Here's an important piece of advice. If you are traveling Aqua class and eat in the Blu restaurant, please note THERE IS NO SEATING FOR TWO. Oh, yes, there are tables for two, but these are about 3 inches from the adjacent table for two. So in effect they are tables for FOUR. If you are honeymooning, hard of hearing, or just want to be alone with your partner and not make small talk with strangers, you are out of luck in Blu.
On this account, Celebrity did screw up with us. We requested a table for two every night in the main dining room. When we arrived for dinner, we were told that, sorry, you're traveling Aqua class, thus your reservation in the main dining room has been cancelled and you are to eat at Blu. That essentially meant that we sat at a table for 4 every night, though we wanted to be alone. I am hard of hearing, so it was quite some agony trying to converse with people at the next table, much of whose conversation I couldn't hear! Be forewarned.
The meals at Blu, by the way, were I would say, uneven. Some dishes were really excellent, but a few were ordinary, and one or two were salted to death and almost uneatable.
Celebrity also screwed up with us on disembarkation. We wanted transfers to central London. However, they gave us the wrong disembarkation number, and we we got off and collected our bags, the bus for central London had left long ago. It was awhile before they could summon up another bus and another driver. Celebrity was certainly apologetic about it and refunded our $200 money for the transfer.