The infinity is definitely showing some age, some rust here and there, some fraying fabric on chairs and probably the most obvious is the state of the cabin bathrooms which are really in need of some overhaul. On the other hand, the crew is outstanding...friendly, always say hello when passing. The food has actually, IMHO, improved....the food on the infinity is actually spiced so if the dish says "spicy", it actually is spicy. I also found that although they use a lot of salt, there seem to be less used on our cruise. Breadsticks were great when they weren't soggy which happened twice in select dining...quickly replaced. Our cabin attendant was terrific and thorough....but of course that varies (read the aqua class cabin review here). The ports are the ports...this is a big ship and it docks where it can...and as with many, if not most cruise ships, that's in whatever container port is available. South America is not Europe. Yes, the infinity was running on one pod, but that didn't cause any issues for our cruise.
We had guest speakers...talking about arctic exploring and auto racing....even though this was a panama canal cruise. No talks on the panama canal (or any other port)...pretty clear that celebrity just wanted to find two speakers on most any topic.
We saw the introduction of the new aqua spa cafe...nothing cooked to order, you just order from a fixed menu and they prepare your small plate on the spot. This is about the fourth try at change for that venue....at some point, they'll get it right.
Select dining worked well on our cruise...almost no wait at all as long as you are willing to dine with others. Something new on our cruise (and perhaps on others), we had a menu, but there was a chef's special entree almost every night...and those were really good (and well seasoned). Hope this becomes a standard offering.
I would not avoid the infinity (or other M-class ships), but at this point, given similar itineraries, I'd book one of the S-class ships first. Prior to the conversion of aft deck 12 to an open air theater with movies running from 10AM to midnight, we actually preferred deck 11 aqua cabins on the M-class to other options...but no more because we use our balcony and like quiet. If the itinerary fits what you want, you'll have a good time on the infinity (or other m-class ship), but be prepared to find reminders that it's getting pretty long on the tooth.
sofa was in pretty bad shape...shower "curtain" might have been the original and shower floor was buckling...mirror had black spots where it's lost it's silver backing. Door to balcony was very difficult to open/close. The only plus is that concierge (and aqua) cabins have about 20 more sq ft than the other balcony cabins.
no global entry, but they routed us to a special fast path line....so it worked out OK. No customs inspection at all...but I think they may do random checks.
We booked a private excursion (for less than Celebrity wanted to see the same sites which would have required two tours). The port is awful and unsafe...with warnings everywhere about leaving on your own. The city is interesting...worth seeing once (with a guide).
I think every cruise in the Caribbean stops in Grand Cayman...and after you've seen sting ray city, there's not much to do. We only get off to wander around and shop (not for bargains...they get too many visitors to bargain very much)..