My wife and I have cruised on Norwegian twice and this was our first time on Carnival. It was like taking a step down from what we had expected. I can only conclude that all the good reviews we read are from people who did't expect much.
The ship is definitely showing it's 30+ years old, and although I read it was dry docked in 2012 for refurbishing, it doesn't show it. The rooms have not been updated and while clean, the plumbing needs work.
Embarkment procedures, yes long lines, but that was expected. The worst part was standing around for a least 30 minutes during muster waiting for guidance on the safety procedures. Everyone stood around waiting to hear about the safety protocol with no updates on when were going to hear anything, while they rounded up all the stragglers.