Gary Bembridge of Tips for Travelers on youtube has some terrific msc videos. He just did an update showing yacht club, etc. on the Virtuosa. I've been pretty much all Carnival up to trying MSC and for me the only thing that was noteworthy in being better (which would vary by the ship obviously) was the SPA. These people are seriously into their spas, oh my.
MSC seems to excel at disorganization and pain in the butt. Expect their customer service to be even worse than anything you've read online. I like to think I'm a pretty easy customer, but the things they couldn't do, the things that took HOURS to fix on the phone were just astonishing.
We're booked on MSC for a couple more but only because they're cheap and go to the ports I want to go to. Otherwise, they're not worth the hassle, at least for me. I looked at canceling our upcoming cruise and switching it over to NCL for a similar itinerary, similar dates, but decided to stick with MSC because for that comparison the spa was better. May live to regret that, we'll see, lol.