We have sailed only with RCI before. We have been getting more and more disappointed with RCI standards and thought we would try Cunard. Being 51 years old, we were a little concerned that Cunard would be too formal and 'sedate' for us. We needn't have worried. We found the whole Cunard experience brilliant, and it put RCI to shame with the level of care and detail Cunard put in to ensure your cruise is as worry-free as possible.
Our cabin was spacious and very clean. We were well looked after by the steward, and, unlike RCI he wasn't constantly knocking on the door. The balcony was big as well (I think you get a bit of extra room on deck 4 as our balcony stuck out further than the ones above. Beware though that some of the balconies on deck 4 (those towards the bow) have metal fronts, not glass like ours). The ship is very well laid out and easy to get around.
We found the food to be superb, both at the Lido and also thee main restaurant. In the Lido, there is a good choice and the quality is excellent. In the main restaurant there is a different choice every night. RCI always seem to have many of the same starters and desserts, whereas with Cunard each night is different, which we liked.