Carnival Corporation historically has tried to preserve the shipboard atmosphere, etc., of the lines that it has acquired, and I see nothing to suggest that it will do otherwise in this acquisition.
The problem is that Carnival Corporation does a lot of tampering behind the scenes, where it's less obvious, to cut costs and raise apparent profits. When that tampering affects things like maintenance schedules, ships become less reliable and start having incidents of the type that we have seen across all of the company's lines. It's enough of a difference so I'll stay away.
Additionally, Carnival Corporation has a history of being less than responsive to problems aboard its ships that affect safety, sanitation, and satisfaction of its passengers -- basically focused on today's bottom line ("it will cost money, so don't do it") rather than bringing back passengers for more cruises in the future.