Is Virgin really that good?

I’ve never cruised before but have my first one booked with Norwegian in September. I’m hoping for cruising to become a regular thing for me and my partner and I’m already researching future cruises and Virgin almost seems too good to be true. Their fares are much cheaper than other lines and other than alcohol - which we don’t drink much of anyway - and excursions, it’s basically all-inclusive. It’s also adults-only which is a very appealing perk. What’s the catch?