I have been on several "expedition" cruises which involved small ships and zodiac landings for hikes, etc. I had always wanted to do a grand Atlantic crossing on an ocean liner, and this was it! The cabin and on-board service staff (especially cabin steward and Britannia restaurant waiters) were outstanding, and the overall experience was quite enjoyable. My cabin was immaculate and very quiet and comfortable.
But there were some surprising problems. Embarkation in New York was AWFUL, worse than a bus terminal. An hour wait in slow-moving line in a large hangar with no ventilation, no benches and no water available to drink. Given the target age group of Cunard, it was pretty shocking. There was one line at the far side for people with disabilities, but it was poorly marked, and, clearly, the majority of passengers are not able to use it. Really unacceptable. Both a friend and I discovered improper charges on our bill on disembarkation day, and the line was way too long to get it remedied on board. I have sent an email to Cunard and got an automatic response saying I would receive a personal response within 2 weeks. Given that it happened to two of us, I can only assume this is not a rare occurrence. So check your billing statement!
It is worthwhile to have breakfast and/or lunch in the peaceful dining room, fussed over by attentive waiters. You feel totally pampered. The Kings Court Buffet offers good food choices (and lots of them) but it is still basically a food court where you have to look for a table and negotiate crowds with plates of food in hand. It was nothing special. The pub is a great place for an informal lunch and a beer. I had room service breakfast once, and it came exactly on time, and exactly as ordered.
It was a pleasure to be in the cabin, always beautifully made up. Bedding was crisp and the mattess and pillows very comfortable. It was too chilly to sit on the balcony for long for most of the trip, but the glass doors made the cabin bright and cheerful.