As others have mentioned, food is very subjective (and can vary restaurant to restaurant, ship to ship). I've enjoyed 13 cruises on NCL so far (twice on the Epic) and only recall two MDR meals that were sub par. Not awful, just not great. Part of that was me trying something "new". There have been far more MDR dinners that were fantastic. It's a great opportunity to find out what you might like! Before our first cruise on the Pride of America we read a lot of reviews and there were so many complaints about the food (with comparisons to Applebees, etc.). We were also worried. After the cruise, I remember thinking "I wonder what the heck that guy has been ordering at Applebees that can even compare to this!" We loved it all!
That said, have there been changes? As far as I can tell from Youtube and CC, YES -- there have been changes on every line! There have been complaints about fewer options being offered in the MDR, but that is the exact same thing we experienced on the Discovery Princess last month. Folks get very nostalgic about certain things, but that's true of everything.
A few years back I decided to reduce my sugar intake and that has limited my options for dessert. Some of the sugar free desserts are better than others (but hey, maybe my scale won't protest so much when I get home). There aren't any sugar free dessert options advertised in the specialty dining restaurants, so I do usually splurge there.
I love NCL and can't wait for my next cruise in 3.5 weeks!
Have a fantastic time!