Britannia Club dining is super. You can have your meals when you want, and the service is exceptional. The headwaiter (Mauro) is Italian and he always took the time to converse with myself and my fiancee and to make us feel comfortable and looked after. You have your own reserved table, which is waiting for you whenever you arrive. You also have the same waiting staff, and our waiter (Mehmet) and assistant waitress (Maya) were very attentive and friendly. Top-notch service to match the top-notch food.
Had I known how good the food would be, I wouldn't have obtained reservations for the QM2's specialty restaurants. Todd English is stylish and the food is exceptional, but I don't know if it was really all that much better than the food in the Britannia Club. They did have a cake ready for my fiancee's birthday dinner, though. Again, great service and a nice change of atmosphere.
The Chef's Galley is a nice experience as well. You get to watch a chef prepare the meal you will eat (or rather a demonstration model) and he narrates the whole process extensively. I didn't understand much, but then I don't cook. The meal (tenderloin, french onion soup, and much more) was tremendous.
I wish the shows on the QM2 were as good as the food. Unfortunately, they were rather uneven. The cabaret singer and the jazz combos (who play the Chart Room) were fantastic, but the rep company was so-so. Some of the singers have great voices. Others... not so much. The "Rock at the Opera" show was particularly ill-conceived.
We had only one port of call on this short trip: Halifax. Nice city, and you could see most of it in a day. We skipped the excursions and just strolled around, and saw the art gallery (excellent). It was a fun day.
I should note that my fiancee was somewhat seasick. Even when the seas are gentle, you can still feel the ship's yaw (an up-and-down motion) so don't believe the hype that on a ship this large you can't get sick. I think you would need to be fairly sensitive to be bothered by it, however.
All in all, this was a great cruise on a great ship, and we really enjoyed the experience. A few tips: get to the ballroom early for the last high tea, and check out the Commodore Club and the bridge viewing area. Enjoy!