We sailed from Southampton to Cape Town - the first leg of QM2's current world cruise. Generally, once everyone (passengers & crew) settled down, it was a fine experience. The ship was full and, at first, things didn't run too smoothly but by the time we reached Madeira everyone was more or less au fait with what to do and where to go etc.
My wife wasn't too happy with the dining experience in the Brittania restaurant, constantly complaining that the food was indifferent but I was less critical. Feeding 2,350 people at two sittings in the evenings will never be more than mass catering.
The entertainment was pretty good (Louis Hoover was outstanding and put on a "free" third concert in response to the acclaim he received). Some of the lecturers were fascinating (Martin Saunders, a BBC wildlife cameraman, for instance, and Peter Hawthorne on Afrikaners - standing room only for that one). There is a fine library on board and the planetarium films were amazing. Each day seemed to pass in a flash - there was no excuse for being bored though some people were.
One common complaint was the nine-day leg at sea from Tenerife to Cape Town -- a very long stretch for passengers and crew which seemed unnecessary as we passed equidistant from Cape Verde islands and St. Helena with Ghana to the east. The fascinating desert excursion in Namibia made up for some of this.
The other common complaint, as ever, was Cunard's absurd alcohol prices - £10 for a glass of wine and a beer. All this does is to reduce sales and encourage passengers to bring their own drink on board.
Our cabin on Deck 4 had a "sheltered" balcony. Before we sailed, we were unsure about this but couldn't upgrade. In the event it was not a problem at all and there was plenty of space and sun.
All in all, a memorable experience.