I was on the same crossing, and I must agree that the food fell short of wonderful in Britannia. I found myself rarely looking forward to meals at Britannia - a number of dishes lacked refinement, being less than ideal in at least one aspect out of visuals, textures and/or taste.
Steaks were a particular low point for me, with the sirloin on one dinner having unchewable gristle as well as being quite tough generally, and the "medium" fillet on the Surf and Turf arriving nearly well done; the half lobster on the same dish was also tiny, no bigger than a decent sized prawn once out of the shell.
King's Court also paled in comparison to the buffet on Celebrity Edge from August this year, which was similar or better in terms of quality of items, but with seemingly about four times the variety of selection.
It was my first ever crossing and had an absolutely wonderful time overall, so I would happily do it again. However, next time it will be either in one of the Grills suites, or I will factor in more dinners in Verandah (which I did enjoy) if I was not.
To be fair, the fish and chips at Golden Lion was spot on (with proper chips, not fries), and Carinthia Lounge quickly became my favourite spot for breakfast with the small dishes that were flavourful and beyond the run-of-the-mill.