MSC status matched us to Diamond (then called Black) from our Norwegian Platinum Plus (now Sapphire.) The process worked well, but it did take some time. It was all online. I had to send copies of our existing cards (which was a screen print since we don't have cards.)
HOWEVER, if you do not sail often enough, you lose your status and start over. We actually booked a Christmas cruise and then found out our status would expire about a month before, so we booked a quick Memorial Day cruise just to maintain our status. (This was all pre-COVID.)
Our "maintain status" cruise was on MSC Seaside and it was a very nice cruise. Beautiful ship, decent crew. Our Christmas cruise was in Yacht Club on MSC Divina and was not good - our butler sucked. We were in the Yacht Club bar for lunch, saw a pizza box and asked if we could have a pizza delivered and were told "No." In the Yacht Club. We have never been told "no" on anything in Norwegian's Haven. That one word turned my wife off MSC pretty much forever.
It is an Italian cruise line based in Switzerland. It attracts a lot of Europeans who do not have the same concepts of personal space and etiquette as Americans (be ready to have people cut in line, crowd next to you, etc). It caters to their tastes, so it is not like Carnival or Norwegian. By the end of the week, I really just wanted a cheeseburger.
I would go again, but it would be because it was really cheap.