We just got back from a week aboard the Constellation. I travelled with my brother (age 39), son (age 15), sister (age 35) and her twin four year old girls, and my aunt (age 59). We all had a fabulous time.
The food, service, and facilities were excellent. Last year, we sailed on RCI's Voyager and had a wonderful time, but a very different experience.
The itinerary for this trip included some beautiful islands and the Constellation is a more elegant ship. However, the entertainment on RCI was much better (ice skating show, a circ de soleil type show, etc.). We went to the specialty restaurant which was fabulous - I was hesitant because I enjoyed the main dining room, but the food was definitely something to write home about! The Fun Factory kids program was terrific. We just can't say enough good things.
The only criticism I have is that the Contellation draws an older crowd and there is more smoking on board than I remember on the Voyager. They seem to allow smoking in a lot of places on the Constellation (one whole side of the ship) and it gets annoying.