My biggest complaint is the lines on the ship for food when there is clearly enough stations available to mitigate that. Also they have a bad habit of shutting down stations at the worst possible time, that being around 4:30PM when you've spent all day on a island and looking for a quick bite to eat...so is everyone else...so the food stations that are open...yup...long lines!!!!
Also I found a lot of people to be rude on the boat, expect to get cut in line quite a bit for food. I know that's not necessarily Carnival's fault, but I've been told by other that Carnival is basically the McDonald's are cruise lines so you get a lower class of people.
Oh and when they do the safety review (which I fully understand needs to be done) expect to waste an hour along with no warning of when they are going to blow the ships horns (those horns make a AC/DC concert seem quite)...little kids were crying from that experience and my ears rang for several days afterwards. The safety review was poorly handled, took us a good 20 minutes to even figure what muster station we were suppose to be in. I have captain fishing boats on the ocean for years...to say I was rather concern with this crews ability to handle an emergency should one arise would be a huge understatement...I found the safety review extremely un-organized and dangerous in my opinion.
Cabin was clean, but no way to see how much you're spending on board via the TV even though they say that's available. I realize AC power is limited on board, but a single outlet in the whole cabin made if difficult to get everything charged up for being off the ship during the day. Lightening system isn't great, why they still use florescent lights now a days is extremely strange. Overall thought he cabin was clean and in good shape.