We were on Regal Princess in June on a Baltic cruise and then again in October on a short 5-day Canada cruise. The cruise in June was wonderful; in October, some deficiencies in dining room service were very evident.
All the problems were in the main dining rooms. For dinner (traditional late), things were extremely slow the first night along but a word with the headwaiter for our area got things straightened out and things were fine the remaining nights. But in the Concerto dining room, used for breakfasts, lunch, and tea, it was a mess. Painfully slow service, forgotten items, and the like. They seemed surprised to have a lot of people show up for tea on a sea day. Things that should have been offered together weren't (for instance, at tea, scones were offered but no one with cream and jam was in even in sight much less right behind).
On the other hand, the other dining venues we used (Alfredo's, Horizon Court, and International Cafe) were fine. I never thought a Maitre'D or other senior hotel/restaurant management people could make that much of a difference on a ship but I did notice that we had a different Maitre'D and Hotel General Manager (as well as others) than in June. The Maitre'D in June was frequently visible in the dining rooms; the one in October wasn't seen other than his ceremonial appearances (staff introductions, champagne waterfall, etc.). Without the boss keeping an eye on things, things tend to slip.
The cabin was as expected. Being almost at the stern, we noticed a lot of the pitching and yawing with some high winds but it was easily tolerable - it is a very stable ship. Adequate room under the bed to store suitcases. A little more closed space and drawers would be nice but we made it work.