We booked this trip early, 9 months before, a trip to Southampton, three weeks in Europe and then return passage to NYC.
It turned out that the Queen Mary 2 did not sell out for the Aug. 19th sailing, and we and our friend traveling alone with us were both upgraded to Princess statements and dining, perhaps because we booked early or were novice Cunarders, we don't know. We did not get upgraded on the return and dined in the Britannia dining room.
In comparison, the Princess room was indeed larger, with a walk in closet even and decent sized bathroom and a larger balcony. We found the Britannia level room entirely satisfactory, however, and we were careful to have a room with an unobscured balcony. The steward at each level was very hardworking and attentive, with the Princess level steward having somewhat better English.
Very pleasant cabin! Great closet space and space to move around - with a wonderful balcony with two teak deck chairs. The bathroom was excellent, excellent shower, although the tub lip is a bit higher than we were used to. And there were ample electric outlets.
Cunard needs to improve the quality of their tv's, telephones (apparently there is no message light), and especially their slow internet, but that is true all over the Queen Mary 2 it seems.
Not fancy but a well run terminal; the staff was very knowledgeable.
The Brooklyn Cruise terminal is as basic as it gets. And they didn't handle the traffic well on embarkation day.