Here's a few observations: I have been on sixteen
DCL cruises with my DW, seven on the Wonder, seven on the Magic and two on the Dream. My last cruise on the Wonder was a year ago, my last cruise on the Magic about 18 months ago and my last cruise on the Dream, a brand new ship, about four months ago. Objectively, each of the ships' maintenance and appearance was about equal. There were a few worn areas and, yes, even rust on the Dream when we sailed her. That's why they are constantly painting it. I will guarantee you that there is even areas of rust on the Fantasy, and it hasn't even had its maiden voyage. Sea air/water plus metal equal rust. Plain and simple.
The Magic and Wonder are closer to fourteen and thirteen years old, respectively, and our first cruises on these ships were in 1999/2000. Since then, depending upon when you sail them, and when their last dry dock was completed, they look a bit better than other times. And I will say unequivocally that both look better in our last few sailings than they looked years previously. But never have we noticed them to be in disrepair or anything close to being worn out. The Dream even had some worn carpet back in September, that I am sure will be replaced and fixed when the next opportunity arises.
As for entertainment, there used to be a live band at the sail away party; however, I really don't remember seeing it on regular cruises for at least five or six years now. No real loss in the experience. Sessions and Cadillac Lounges are tremendous and the piano players add to the experience. Both of those lounges tend to be much more crowded later in the evening after both dinners and shows and only moderately attended in the early evening. They have always been that way. Unfortunately, the Dream has no similar lounge and no piano player at all, which is disappointing.
In summary, although expectations and experiences vary among guests, at least in our experiences back from 1999, we have not seen a measurable decline in the amenities, experiences or maintenance of any of the ships. Enjoy your cruise.