I and my family cruised many times and never had such bad experience as we did on Meraviglia. Only positive is that this ship is new, but very bad design from comfort and efficiency stand point. You can't enjoy your vacation on this ship. It is designed to create issues at every step. Customer was not on their mind when they decided to release this ship. Too many passengers (4500) and not enough accommodation and service logistics. Anyone who rates this ship as good or excellent, has never been on any other ships before or got their travel for free and got paid to travel :-).
Everything about this nightmare cruise started when I logged in to my MSC account to register for check-in and ended at disembarkation.
You can't check-in and get your e-ticket while you are logged in. By the time I figured this out, it was too late to check in online, so I decided to do this at port (Miami).